Self-Assessment Color Review
Avian Medicine and Surgery Second Edition
Self-Assessment Color Review
Avian Medicine and Surgery Second Edition Edited by
Neil A. Forbes
Great Western Exotics Swindon, U.K.
David Sanchez-Migallon Guzman School of Veterinary Medicine, UC Davis California, U.S.A.
CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2017 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed on acid-free paper International Standard Book Number-13: 978-1-4987-0351-2 (Paperback) This book contains information obtained from authentic and highly regarded sources. While all reasonable efforts have been made to publish reliable data and information, neither the author[s] nor the publisher can accept any legal responsibility or liability for any errors or omissions that may be made. The publishers wish to make clear that any views or opinions expressed in this book by individual editors, authors or contributors are personal to them and do not necessarily reflect the views/opinions of the publishers. The information or guidance contained in this book is intended for use by medical, scientific or health-care professionals and is provided strictly as a supplement to the medical or other professional’s own judgement, their knowledge of the patient’s medical history, relevant manufacturer’s instructions and the appropriate best practice guidelines. Because of the rapid advances in medical science, any information or advice on dosages, procedures or diagnoses should be independently verified. The reader is strongly urged to consult the relevant national drug formulary and the drug companies’ and device or material manufacturers’ printed instructions, and their websites, before administering or utilizing any of the drugs, devices or materials mentioned in this book. This book does not indicate whether a particular treatment is appropriate or suitable for a particular individual. Ultimately it is the sole responsibility of the medical professional to make his or her own professional judgements, so as to advise and treat patients appropriately. The authors and publishers have also attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www. copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com
Contents Preface ........................................................................................................vii Contributors ................................................................................................ix Dedications, Acknowledgments, Photo Credits ........................................ xiii Abbreviations..............................................................................................xv Broad Classification of Cases ....................................................................xvii Questions ......................................................................................................1 Answers ....................................................................................................125 Index .........................................................................................................349 Also available in the self-assessment color review series ...........................363
Preface The first edition of Avian Medicine SACR was published in 1998 and has proven to not only have been popular, but many current key workers in the field have reported that this was the text that inspired their careers in avian medicine. Since the first edition, the whole movement of ‘evidence-based medicine’, advancing recognition of ‘specialization in avian medicine’ and improved training in exotic medicine at an undergraduate level in many veterinary schools has thankfully advanced the discipline further. Concurrently, owners now have a greater understanding of diagnostics and potential treatments, which in turn fuels a greater expectation in respect of outcomes. So the time has come to update and renew this fun and simulating text. There are many quality reference texts on avian medicine and surgery that offer detailed in-depth information; however, accessing this information can be laborious and time consuming. This book, along with others in the self-assessment color review series, is designed to assess one’s level of knowledge and offers comprehensive, clinically-oriented information that can be quickly accessed, easily understood, and applied. The book covers a wide range of disciplines, organ systems, and species, but is not as all-inclusive as a text would be. The questions are presented in the same way clinical cases would be presented on a daily basis, challenging the reader to real clinical situations and, in most cases, offering a comprehensive solution to the question. In this edition we have attempted to cover all the currently important and salient clinical conditions.In comparison with the first edition, greater emphasis is paid to recent diseases, techniques and treatments (e.g. endoscopy, cardiology, therapeutics, virology, PCR testing, and new surgical techniques). Whilst many readers found the previous format with questions on one page and answers on the next easy to follow and use, this newer format has questions at the beginning and answers at the end. This new format has removed any ‘answer length restraints’, enabling us to provide more complete and thorough answers, which we believe will be appreciated by readers.In addition, many of the answers are now referenced, giving readers the opportunity to follow up with further investigation and reading on specific topics. The book is designed to be fun to read while at the same time being instructive. This type of learning has proven to be most effective for neophyte avian practitioners as well as experienced clinicians by guiding the reader through the main decisionmaking processes. In compiling this book we have enlisted contributions from leading international authorities with diverse fields of expertise. We are sure that there will be varying opinions on some of the material presented and that products discussed will not be available in all countries. References are included at the end of most of the answers.
We hope that the reader will find this book a useful learning tool and at the same time enjoy the learning process. Neil A. Forbes David Sanchez-Migallon Guzman
Contributors Roberto F. Aguilar Institute of Veterinary, Animal and Biomedical Sciences Massey University Palmerston North, New Zealand Alberto Rodriguez Barbon Durrell Wildlife Conservation Trust Trinity, Jersey, U.K. Hugues Beaufrère Ontario Veterinary College University of Guelph Guelph, Ontario, Canada R. Avery Bennett Veterinary Clinical Sciences Louisiana State University Baton Rouge, Louisana, U.S.A. Alan Beynon St David’s Poultry Team Dorrington, U.K. João Brandão Center of Veterinary Health Sciences Oklahoma State University Stillwater, Oklahoma, U.S.A. Terry W. Campbell Colorado State University Fort Collins, Colorado, U.S.A.
Stephen Divers University of Georgia Athen, Georgia, U.S.A. Bob Doneley School of Veterinary Science University of Queensland Brisbane, Australia Neil Forbes Great Western Exotics Swindon, U.K. Ady Y. Gancz Koret School of Veterinary Medicine Hebrew University of Jerusalem Bet-Dagan, Israel Jennifer Graham Tufts Cummings School of Veterinary Medicine North Grafton, Massachusetts, U.S.A. Cheryl Greenacre The University of Tennessee Knoxville, Tennessee, U.S.A. Claire Grosset Veterinary Medicine University of Montréal Montréal, Canada
Laurel Degernes NCSU College of Veterinary Medicine Raleigh, North Carolina, U.S.A.
Vanessa L. Grunkemeyer University of New Hampshire College of Life Sciences and Agriculture Durham, New Hampshire, U.S.A.
Mathias Dislich Parque das Aves Foz do Iguaçu, Brazil
David Sanchez-Migallon Guzman School of Veterinary Medicine UC Davis, California, U.S.A.
Minh Huynh Centre Hospitalier Vétérinaire Fregis Paris, France
Christal Pollock Lafeber Company, Cornell Illinois, U.S.A.
Michael Jones The University of Tennessee Knoxville, Tennessee, U.S.A.
Julia Ponder The Raptor Center University of Minnesota St. Paul, Minnesota, U.S.A.
Krista Keller University Hills Animal Hospital Denver, Colorado, U.S.A. Isabelle Langois Veterinary Medicine University of Montréal Montréal, Canada
Drury Reavill Zoo/Exotic Pathology Service Carmichael, California, U.S.A.
Crosta Lorenzo Veterinari Montevecchia Montevecchia, Italy
April Romagnano Avian & Exotic Clinic of Palm City Palm City, Florida, U.S.A.
Christoph Mans University of Wisconsin-Madison Madison, Wisconsin, U.S.A.
Mikel Sabater Avian Reptile and Exotic Pet Hospital University of Sydney Sydney, Australia
Ricardo de Matos College of Veterinary Medicine Cornell University Ithaca, New York, U.S.A. Deborah Monks Brisbane Bird and Exotics Veterinary Service Macgregor, Australia Glen Olsen USGS Patuxent Wildlife Research Center Patuxent Veterinary Hospital Laurel, Maryland, U.S.A. Joanne Paul-Murphy School of Veterinary Medicine UC Davis, California, U.S.A.
Shane Raidal Charles Sturt University Wagga Wagga, Australia
Jaime Samour Wildlife Division Wrsan, Abu Dhabi, U.A.E. Peter Sandmeier Kleintier- und Vogelpraxis Baden, Switzerland Nico Schoemaker Utrecht University Utrecht, TheNetherlands Dale Smith Ontario Veterinary College University of Guelph Guelph, Ontario, Canada
Stephen Smith Tiggywinkles Wildlife Hospital Haddenham, Bucks, U.K.
Morena Bernadette Wernick ExoticVet GmbH Jona, Switzerland
Brian Speer Medical Center for Birds Oakley, California, U.S.A.
Nicole Wyre Zodiac Pet & Exotic Hospital Hong Kong, China
Jonathan Stockman Waltham Centre for Pet Nutrition Melton Mowbray, U.K.
Yvonne van Zeeland Utrecht University Utrecht, TheNetherlands
Jens Straub Animal Clinic Dr. Krauss Duesseldorf GmbH Department of Avian and Reptile Medicine Duesseldorf, Germany
Dedications To my wife Karen for her support and tolerance and my daughters Katrina and Sarah-Jane, acknowledging the many hours when their father was too busy to be with them. NF To Oma, with all my love. To my parents, Pilar and Alfonso, and my siblings Francisco, Ester, and Alberto, for their love and support even in the distance. To those who inspired me, intentionally or unintentionally, to be the person and the veterinarian that I am today. To the future generation of avian veterinarians who will care for our feathered friends. DG
Acknowledgments My eternal thanks to my mentor, Professor JohnE Cooper, for his initial encouragement and introduction into avian medicine at the start of my career, and his support and enthusiasm throughout my career. To all those who have assisted in the development and recognition of Veterinary Specialization. NAF I would like to thank all the authors for their effort and contribution to this issue, as well as the residents, students, and technicians that participated in some of the cases illustrated. Also, Iwould like to thank my colleagues Joanne, Michelle, and Jessica, who I share with all the daily challenges at work; without their continuous support, I would not have been able to accomplish this task. Lastly, I would like to thank the CRC Press team and Neil for the opportunity given to serve as co-editor of this book, and for their support and guidance. DG
Photo Credits 24a, b 60a–c 73 77 153 162 184
Dr. J. Brandão Dr. Noemie Summa Dr. Jens Straub Dr. Thereza Rizzi Dr. Matthew Grabovsky Dr. Neil Forbes Dr. Marisa Pérez
189 192 193 195 197 220 266
Dr. N. Chai Dr. J. Samour Dr. Eduardo Huguet Dr. Peter Coutteel Dr. T. Dutton LafeberVet LafeberVet
Abbreviations ALP AST BUN BW CBC CK COX CPR
alkaline phosphatase aspartate aminotransferase blood urea nitrogen bodyweight complete blood count creatine kinase cyclooxygenase cardiopulmonary resuscitation CRI constant rate infusion CT computed tomography DNA deoxyribonucleic acid ECG electrocardiography/ electrocardiogram EDTA ethylenediaminetetraacetic acid ELISA enzyme-linked immunosorbent assay ESF external skeletal fixator GGT gamma-glutamyltransferase GLDH glutamate dehydrogenase GnRH gonadotropin-releasing hormone Hb hemoglobin IM intramuscular/intramuscularly
IN IO IV LDH LDL MCH
intranasal/intranasally intraosseous intravenous/intravenously lactate dehydrogenase low-density lipoprotein mean corpuscular hemoglobin MCHC mean corpuscular hemoglobin concentration MCV mean corpuscular volume MRI magnetic resonance imaging NaCl sodium chloride NSAID nonsteroidal antiinflammatory drug OD oculus dexter (right eye) OS oculus sinister (left eye) PCR polymerase chain reaction PCV packed cell volume PO per os/orally RBC red blood cell RT-PCR real-time polymerase chain reaction SC subcutaneous/subcutaneously UV ultraviolet WBC white blood cell
Broad Classification of Cases (Cases may be classified under more than one category)
8, 33, 58, 65, 88, 95, 97, 131, 147, 173, 191, 203, 208, 211, 228, 230, 231, 234, 241
82, 133, 145, 226, 262
Anatomy 11, 19, 24, 47, 48, 52, 56, 64, 83, 89, 102, 111, 117, 119, 131, 132, 137, 141, 148, 165, 176, 179, 183, 189, 211, 214, 228, 233, 246, 256, 257, 259, 264, 270
Bacterial infection 10, 34, 40, 48, 52, 62, 83, 102, 110, 111, 119, 129, 144, 145, 149, 161, 164, 171, 178, 202, 215, 219, 225, 237, 242, 244, 255, 262
Clinical pathology 3, 4, 10, 14, 15, 18, 26, 29, 35, 36, 40, 41, 44, 46, 58, 59, 61, 63, 67, 69, 76, 77, 78, 99, 101, 107, 109, 134, 140, 155, 161, 164, 176, 177, 178, 198, 206, 209, 219, 243, 263
Cytology 14, 16, 20, 37, 40, 53, 58, 77, 78, 82, 101, 123, 140, 155, 163, 164, 188, 215, 244, 248, 255, 259
10, 14, 15, 21, 50, 89, 167, 189, 209, 216, 220, 266
3, 17, 21, 25, 49, 72, 96, 104, 121, 122, 133, 158, 160, 178, 180, 190, 198, 204, 213, 216, 224, 240, 245, 247, 251, 266, 270
Beak and head kinetics
21, 96, 102, 130, 141, 160, 228, 252
1, 3, 4, 7, 10, 12, 14, 15, 16, 18, 20, 22, 26, 30, 31, 34, 35, 40, 44, 45, 50, 53, 57, 58, 59, 61, 63, 67, 68, 72, 76, 80, 82, 87, 90, 93, 95, 96, 101, 104, 109, 113, 114, 123, 125, 129, 134, 135, 138, 140, 143, 158, 161, 178, 181, 187, 195, 198, 206, 209, 215, 237, 248, 249, 268
Behavior 9, 38, 51, 75, 103, 118, 133, 265, 267,271
Biochemistry 3, 4, 10, 15, 18, 26, 35, 36, 41, 46, 50, 63, 67, 76, 109, 198, 206, 209, 243
Emergency and critical care
59, 74, 251
15, 36, 50, 55, 73, 106, 147, 151, 231, 241, 242, 250
22, 26, 39, 56, 73, 87, 88, 93, 201, 239, 254, 269
24, 148, 198, 243
1, 5, 37, 48, 58, 79, 111, 125, 130, 146, 151, 165, 176, 184, 186, 192, 199, 203, 210, 216, 234, 250, 256
18, 22, 42, 47, 55, 85, 94, 106, 117, 120, 129,139, 177, 187, 188, 197, 202, 206, 208, 225, 233, 246, 268, 269
26, 35, 37, 40, 58, 96, 107, 145, 149, 161, 164, 171, 195, 219, 226, 249, 262
1, 3, 23, 32, 37, 38, 41, 45, 46, 59, 68, 71, 77, 94, 95, 119, 126, 133, 149, 162, 167, 169, 197, 200, 201, 254
Game birds/poultry 7, 12, 27, 30, 31, 32, 57, 68, 69, 80, 84, 86, 110, 124, 131, 134, 202
Gastroenterology 3, 38, 40, 54, 60, 67, 82, 123, 133, 149, 154, 150, 161, 170, 171, 172, 187, 188, 195, 215, 217, 235, 249, 250, 258, 260
20, 22, 65, 66, 113, 136, 181, 184, 193, 222, 223, 233, 262, 268
Oral 34, 156, 171, 215, 219
3, 4, 10, 15, 29, 35, 36, 44, 61, 67, 78, 101, 107, 140, 155, 198, 209
6, 8, 43, 71, 74, 78, 88, 92, 94, 98, 100, 105, 126, 128, 132, 137, 141, 143, 154, 169, 175, 212, 220, 221, 222, 224, 228, 241, 253
1, 16, 21, 67, 87, 133, 186, 254, 255
41, 100, 127, 152, 157, 168, 174, 194, 229
14, 17, 21, 30, 44, 53, 57, 60, 78, 84, 86, 104, 112, 133, 134, 139, 140, 146, 156, 160, 164, 176, 177, 182, 192, 195, 204, 205, 219, 222, 226. 232, 235, 236, 238, 263
46, 76, 93, 148, 161, 198
44, 104, 163, 183, 190, 195, 196, 205, 226, 237, 259
Neonatology 45, 91, 100, 169, 180, 205, 213, 224, 236, 245, 258, 260
Neoplasia 7, 24, 80, 88, 96, 105, 108, 122, 123, 125, 171, 185, 190, 207, 210, 218, 250, 261
Pathology 16, 32, 34, 44, 47, 56, 70, 72, 77, 80, 82, 84, 93, 105, 109, 110, 112, 114, 115, 117, 124, 125, 135, 139, 146, 148, 150, 158, 159, 163, 164, 169, 177, 185, 188, 195, 196, 217, 218, 219, 226, 231, 237, 244, 248, 250, 254, 255, 258, 261
Physiology 2, 11, 19, 50, 64, 68, 115, 119, 121, 131, 132, 137, 148, 181, 214, 223, 257, 264, 270
112, 113, 120, 122, 126, 128, 132, 136, 154, 155, 156, 170, 173, 175, 177, 181, 182, 182, 183, 184, 192, 197, 200, 206, 208, 219, 221, 222, 236, 238, 241, 251, 253, 268
53, 62, 129, 177, 180, 199, 213, 216, 225, 242, 255
Proventricular dilatation disease
60, 150, 159, 188, 249
2, 7, 12, 31, 41, 51, 63, 84, 91, 103, 110, 116, 126, 127, 134, 149, 152, 157, 165, 166, 168, 174, 180, 183, 189, 194, 202, 218, 224, 229, 231, 234, 235, 259, 260
Psittacine beak and feather disease 29, 72, 90, 158
Psittacines 3, 4, 8, 9, 15, 18, 20, 21, 22, 23, 26, 29, 33, 36, 37, 38, 39, 42, 45, 46, 48, 50, 51, 54, 56, 60, 63, 65, 67, 70, 72, 73, 75, 76, 77, 82, 84, 87, 88, 90, 93, 96, 97, 99, 100, 102, 103, 105, 106, 108, 116, 117, 118, 121, 123, 125, 132, 133, 141, 143, 146, 149, 150, 151, 155, 158, 159, 160, 161, 165, 167, 168, 171, 177, 178, 186, 187, 188, 198, 199, 207, 209, 210, 215, 218, 228, 229, 230, 231, 233, 234, 239, 243, 245, 248, 249, 252, 257, 260, 261, 263, 264, 269
Radiology (radiography, CT, andMRI) 11, 24, 26, 35, 39, 42, 43, 47, 55, 60, 63, 73, 81, 87, 94, 95, 120, 123, 126, 128, 130, 138, 143, 151, 154, 175, 187, 207, 221, 246
Raptors 6, 13, 16, 19, 24, 25, 34, 35, 41, 43, 49, 52, 55, 59, 66, 74, 78, 83, 85, 92, 94,
17, 91, 139, 169, 189, 224, 258
100, 141, 169, 216, 245,
Respiratory 26, 27, 32, 35, 37, 38, 39, 57, 58, 84, 86, 88, 95, 105, 107, 131, 151, 176, 182, 185, 192, 215, 222, 227, 260, 264
Rhamphastids 1, 32, 40, 57, 130, 164, 203, 232
Surgery 28, 46, 83, 95, 97, 105, 116, 123, 125, 128, 130, 142, 149, 151, 153, 162, 170, 172, 179, 186, 190, 202, 203, 210, 218, 230, 231, 245, 260
Therapeutics 8, 16, 22, 30, 34, 37, 42, 44, 51, 53, 58, 61, 62, 73, 80, 82, 84, 86, 88, 89, 104, 108, 109, 110, 120, 123, 124, 133, 134, 136, 150, 156, 160, 171, 176, 184, 191, 192, 195, 198, 200, 202, 206, 208, 213, 215, 219, 222, 225, 226, 227, 236, 238, 241, 242, 255, 263, 269
13, 35, 37, 42, 53, 54, 60, 61, 81, 107, 120, 133, 136, 144, 161, 172, 180, 200, 201, 217, 227, 233, 247, 269
2, 11, 14, 47, 61, 64, 71, 81, 95, 107, 114, 115, 135, 144, 153, 176, 185, 193, 211, 217, 235, 244, 246, 247, 250, 262
Ultrasound 7, 30, 31, 39, 73
Urogenital 7, 12, 51, 63, 64, 84, 99, 108, 109, 111, 115, 116, 117, 133, 153, 161, 165, 185, 189, 199, 202, 218, 230, 231, 243
Virology 25, 27, 29, 35, 60, 62, 68, 72, 80, 90, 96, 106, 110, 114, 125, 133, 135, 145, 150, 158, 159, 161, 163, 164, 171, 188, 196, 204, 207, 213, 218, 220, 225, 248, 249, 262
Welfare 75, 103, 107, 133, 191, 265, 267, 271
Wildlife/rehabilitation 6, 11, 13, 24, 55, 66, 78, 85, 92, 107, 115, 136, 137, 140, 144, 173, 208, 211, 219, 220, 253, 262, 268
Zoonosis 82, 129, 133, 145, 178, 226, 262
Questions CASE 1 An adult male red-breasted toucan (Ramphastos dicolorus) underwent a routine health examination, which included a coelioscopy (1a–c). The liver appeared enlarged but, most noticeable, the surface of the organ was replaced with generalized yellow–brown discoloration. 1a
1 What are the main differential diagnoses? 2 What complementary test would you request or perform? 3 How would you treat this condition?
CASE 2 A local zoo is housing a flock of 15 Chilean flamingos (Phoenicopterus chilensis). They have held the birds for 4 years. The birds have access to a pond and a large beach with soil substrate (2). The zoo would like to breed them; however, to date, they have not been successful. 2
1 What advice could you give to improve reproductive success in this collection? 2 List some possible causes of low egg fertility in flamingo flocks? What management techniques can be used to overcome this difficulty? 3 What management actions can be taken to reduce hand-reared chick mortality during the first days of life?
CASE 3 A 10-year-old male sulphur-crested cockatoo (Cacatua galerita galerita) is presented with a history of intermittent vomiting (2–3 times weekly), reduced appetite, and feather damaging behavior. The client reports that the bird is fed nothing but sunflower seed and a vitamin–mineral supplement occasionally in its drinking water. On physical examination the bird is obese, weighing 1,140 g (normal weight 800–1,000 g) and with substantial fat deposits over the flanks and ventral body. The crop contains a mixture of fluid and soft ingesta. There is feather loss over the back and ventral body. There is no coelomic distension, but palpation elicits a painful response from the bird. You collect blood from the bird and submit it for hematology and biochemical analysis. The results are shown below. Erythrocyte morphology normal; heterophils show 3+ toxic changes. Hematology Analyte Packed cell volume (%) Estimated white cell count (× 10 /L) 9
Biochemistry AST (U/L) CK (U/L) Bile acids (µmol/L; µg/mL) GLDH (U/L) Amylase (U/L) Uric acid (µmol/L; mg/dL)
Urea (mmol/L; mg/dL)
Glucose (mmol/L; mg/dL)
Calcium (mmol/L; mg/dL)
Phosphorus (mmol/L; mg/dL)
Cholesterol (mmol/L; mg/dL)
Triglyceride (mmol/L; mg/dL)
Total protein (g/L; g/dL)
1 What is your problem list, differential diagnosis, and most likely diagnosis? 2 What further diagnostics could be used to confirm your tentative diagnosis? 3 How would you treat this patient?
Questions CASE 4 An adult female blue-crowned conure (Thecocercus acuticaudata) presented for lethargy, anorexia, and reluctance to open the eyes. Whole body radiographs indicated hepatomegaly. The plasma chemistry profile revealed a mild increase in creatine kinase of 1,413 IU/L, an aspartate aminotransferase of 407 IU/L, and anormal total protein of 22 g/L (2.2 g/dL). The complete blood cell count is as follows:
Total protein Heterophils Lymphocytes Monocytes Eosinophils Basophils PCV g/L (g/dL) (by × 109/L × 109/L × 109/L × 109/L × 109/L % refractometer)
1 How should one interpret the complete blood cell count? 2 How should one interpret the image of the blood film (4)? 3 What is the significance of the cells in the image of the blood film?
CASE 5 1 Describe suitable endoscopy instrumentation required for the following procedures: • Coelioscopy with kidney and liver biopsies in a 1 kg raptor. • Tracheoscopy in a 400 gram parrot. • Air sac tube placement in a 400 gram parrot. • Cloacoscopy in a 3 kg goose. 2 Contrary to reptile and mammal coelioscopy/laparoscopy, why is CO2 insufflation contraindicated and not required for avian coelioscopy? 3 When performing endoscopy and endosurgery within the avian air sac system, why is it important to ensure that there is a snug skin–endoscope interface and that all sheath ports are closed?
CASE 6 A 4.3 kg adult female bald eagle (Haliaeetus leucocephalus) presents to your clinic after being hit by a bus. The bird is depressed and currently not a good anesthetic candidate. Radiographs are obtained (6a, b).
1 What are your main concerns on initial evaluation? 2 Describe how you would initially stabilize this fracture. 3 What fixation method would you use for surgical repair?
CASE 7 You are presented with a backyard chicken for evaluation of decreased appetite and activity level, lack of egg production, and coelomic distension. Onphysical examination, the most relevant finding is severe coelomic distension. The coelom is relatively soft and no masses can be palpated. An ultrasound image of the coelomic cavity is shown (7a). On further evaluation of the coelom, a mixed echogenicity structure was identified dorsal to the ventriculus and caudodorsal to the liver and heart (7b). The results of a postmortem examination are shown (7c). 7a
Questions 1 Based on the physical examination findings and the features of 7a, what is the cause of the coelomic distension in this hen? 2 Based on the clinical history, physical examination findings, ultrasound findings, and postmortem findings, what is the most likely diagnosis for this case? 3 What are the treatment options (medical and/or surgical) for this case?
CASE 8 A double yellow-headed Amazon parrot (Amazona orathrix) is presented with a left tibiotarsal fracture. The owner reports that this happened this morning during playing. The bird appears quiet 8 but responsive, and is lame and not weight bearing on the left leg. The owner expresses interest in surgical repair of the fracture and hospitalization during the initial postoperative period (8). 1 How would you manage pain in this patient (1) during the preoperative period, (2) during the intraoperative period, and (3) during the postoperative period?
CASE 9 An owner consults you because she has been having difficulties with getting her African grey parrot (Psittacus erithacus) to step up onto her hand so that she can place it back into its cage. The problem has progressed to such an extent that she now cannot even approach the bird with her hand when it is sitting on top of the cage, without the bird 9 lunging towards her and biting her (9). She is desperate and would appreciate your advice on how to improve this situation, as the biting has become progressively worse and more forceful, resulting in serious bite injuries to her fingers. To better understand problem behavior and be able to design a suitable treatment plan, a so-called functional assessment, which describes the functional relationship between the parrot’s behavior (B), its antecedents (A), and consequences (C), and predicts the parrot’s future behavior on the basis of this relationship, is deemed essential. 1 Conduct a functional assessment of this African grey parrot’s behavior. Include a description of the ABCs as well as a prediction of the parrot’s behavior in your analysis. In the situation as described above, so-called operant learning has taken place by which the bird has learned that by its behavior it is able to operate (control) its environment to obtain a certain effect. Four types of operant learning can be distinguished (i.e. positive and negative reinforcement, and positive and negative punishment). 2 Which of the following types has taken place in this situation? 3 Describe the different interventions that could be considered in this behavior modification plan to reduce the biting and/or prevent injury to the owner’s hand.
CASE 10 Many avian focused practices have in-house laboratories providing hematologic and biochemical results for their patients. This represents a significant investment in both capital and labor for the practice, and the purchase and use of such equipment has to be carefully considered. 1 List the advantages and disadvantages of in-house laboratory testing. 2 List the advantages and disadvantages of external laboratory testing.
Questions CASE 11 A flesh footed shearwater (Puffinus carneipes) is presented for rehabilitation following a storm with heavy winds. The bird is bright, alert, and responsive, feather examination shows good water proofing, and it appears ready for release. The bird was windblown on to land, and otherwise appears healthy. Survey radiographs show a bilateral elongated mineral opacity cranial to the elbow in the propatagium (11a, b). 11a
1 What is the clinical significance of these radiographic findings? 2 What is the name for this structure? 3 What is its function?
CASE 12 A reproductively active 1-yearold Rhode Island Red hen (Gallus gallus domesticus) presented on account of a decrease in egg laying, lethargy, and anorexia for a period of 5 days. The owner had noticed a white to yellow thick discharge from the cloaca (12).
1 What is the most likely organ system involved and the cause of the presentation?
2 What are the recommended diagnostic tests?
3 What is the suggested treatment and underlying agent?
CASE 13 The police are investigating a suspected wildlife poisoning incident and seek your advice. After three red kites (Milvus milvus) have been found poisoned locally over the last 4 months, they visit a local farmer and locate six illegal poisons. The aged farmer (84 years old) reiterates that he hates raptors, stating that the kites pick up and fly off with his piglets, but denies having poisoned them. Two of the three dead birds were located on his property, but one was found dead some 2km away. Each bird was submitted to a full postmortem examination. Mevinphos was found in the mouth or crop of each bird, 13 at 6×, 7×, and 6.5× LD50 levels. The third bird died in April (springtime, 13). It was a female, was missing some feathers on the back of its neck, and showed marked follicular development on the ovary. The question posed to you, in relation to the bird that was found dead 2 km away from the farm, is whether it could have ingested poison from the farm, the point being that if the third bird was poisoned by someone else, then there is a possibility that the first two could also have been poisoned by someone else and as such a prosecution would be unrealistic. 1 Would a red kite be able to carry away piglets? 2 Would the red kite that had consumed a 6–7× LD50 of Mevinphos be able to fly 2 km following ingestion? If not, what other explanations are possible, and what further action would you take to investigate the case? 3 What relevance have the findings on the third bird?
CASE 14 A 2-year-old African penguin (Sphenicus demersus) housed in an outdoor enclosure is presented for lethargy, biliverdinuria, and anorexia. The physical examination is unremarkable. Radiographs are obtained under general anesthesia and are normal. You want to collect a blood sample for a CBC and biochemistry panel.
1 Where are the blood sampling sites located in Spheniciformes? 2 Which hemoparasites might be causing these clinical signs? 3 What diagnostic tests can be performed to screen for these hemoparasites?
Questions CASE 15 A 10-year-old female African grey parrot (Psittacus erithacus) is presented to your practice with a history of nonspecific signs of illness, duration 2–3 days, including a reduction in food and water intake, severe depression, a fluffed and ruffled appearance, as well as vomiting or regurgitation. The bird weighs 390 g. Although the owner reports a history of diarrhea, on physical examination the fecal component of the droppings is normal while the urine component is larger than normal. During the physical examination, the parrot is estimated to be approximately 8% dehydrated. Hematology PCV RBC Hb MCV MCH MCHC WBC Heterophils Lymphocytes Monocytes Eosinophils Basophils Biochemistry ALP Amylase AST Calcium Chloride Cholesterol CK Glucose LDH Phosphorus Uric acid Sodium Potassium Protein (total) Albumin Globulin A:G ratio Osmolality
SI units U/L U/L U/L mmol/L mmol/L U/L mmol/L U/L mmol/L µmol/L mmol/L mmol/L g/L g/L g/L mOsm/kg
Units % 106/µL g/dL fl pg g/dL 109/L 109/L 109/L 109/L 109/L 109/L
Patient value 60 4.5 13 160 47 30 8.2 6.2 1.8 0.12 0.08 0
Patient value 120 470 257 2.4
Reference interval 12–160 415–626 100–350 2–3.25
10.36 57.5 22 398 1.91 536 160 3.1 33 15 18 0.8 334
4.14–11 123–875 10.45–19.25 150–450 1–1.74 238–595 134–152 2.6–4.2 30–50 15.7–32.3
Reference interval 40–55 2.4–4.5 11–16 90–180 28–52 23–33 5–15 4.6–7.5 1.9–5.1 0–0.2 0–0.1 0–0.1 Old units
mg/dL mEq/L mg/dL
9.6 140 400
mg/dL mg/dL mEq/L mEq/L mg/dL g/dL g/dL
5.9 9 160 3.1 3.3 1.5 1.8
3.2–5.4 4–10 134–152 2.6–4.2 3–5 1.57–3.23
1 What route would you use to administer fluids in this patient? 2 What type of fluid, how much volume, and at what rate would be most appropriate? 9
CASE 16 A female gyrfalcon (Falco rusticolus) was taken to a veterinary hospital for clinical examination. The falcon had been maintained in a captive breeding facility, having been recently imported into the UK from the Middle East. The owner reported the passing of pistachio green urates for the past 10 days, reduced appetite, and progressive 16 weight loss. On examination, the falcon showed a body condition of 3/5 and was bright and alert. The falcon was admitted for treatment and boarding. Unfortunately, the falcon died overnight prior to any diagnostic analyses or any treatment being provided. On postmortem examination the liver was grossly enlarged, mottled in color, and looked firm and waxy in appearance (16). Histopathology revealed extensive amorphous eosinophilic extracellular deposits (95%), consistent with amyloid, across the parenchyma of the liver and other organs, notably the spleen and kidneys. This was confirmed after staining the slide using Congo red stain technique. The results suggest the amyloid was amyloid AA. 1 Based on the clinical history and gross postmortem findings, what are your differential diagnoses?
2 What diagnostic test would you perform to confirm the diagnosis? 3 Is amyloidosis likely to be the cause of death? How can you treat amyloidosis? Can amyloidosis be prevented?
CASE 17 The feather of an ostrich (Struthio camelus) is shown (17). 17
1 What abnormality is visible on this feather, and what is its cause?
2 What is the significance to the individual ostrich and to the flock? management actions are required to deal with the problem illustrated?
Questions CASE 18 A 7-year-old female intact Congo African grey parrot (Psittacus erithacus) presents because she has had a seizure at home. She is on a commercial seed diet with some table food as well. When presented at the hospital, she is no longer seizuring but is weak and unable to perch. A blood sample is collected for a biochemistry panel. Parameter AST (U/L) Bile acid (µmol/L) Calcium, total (mmol/L) (mg/dL) Cholesterol (mmol/L) (mg/dL) CK (U/L) Glucose (mmol/L) (mg/dL) Phosphorus (mmol/L) (mg/dL) Potassium (mEq/L) Protein, total (g/L) (g/dL) Albumin (g/L) (g/dL) Globulin (g/L) (g/dL) Sodium (mEq/L) Uric acid (µmol/L) (mg/dL)
523 22 1.7 (6.8) 6.47 (251) 1,348 19.04 (343) 1.07 (3.3) 3.9 46 (4.6) 31 (3.1) 15 (1.5) 142 333 (5.6)
100–350 18–71 2–3.24 (8–13) 3.88–10.99 (160–425) 123–875 10.55–19.43 (190–350) 1.03–1.74 (3.2–5.4) 2.6–4.2 30–50 (3–5) 15.7–32.3 (1.57–3.23) 14.3–17.7 (1.43–1.77) 134–152 238–595 (4–10)
1 What is the most likely cause of this bird’s seizure? 2 If hypocalcemia is suspected based on clinical signs and history, but total calcium levels are within normal limits, what additional test should be considered? 3 What other analyte should be evaluated in this patient if initial treatment to increase the calcium level is not effective? 4 What treatment should be given immediately to prevent another seizure?
CASE 19 In some avian species (e.g. owls, falcons, bitterns, gannets) one claw is modified into a comb-like structure (19). 1 What is the name of this claw? In
which digit is it found? 2 How many phalanges integrate this digit? 3 What are the two main anatomic structures in the claws of birds of prey?
CASE 20 A young blue crown conure (Thectocercus acuticaudatus) presented with unilateral blepharospasm, reddened conjunctiva, corneal edema, and multiple 0.25–0.5 mm vascularized anterior stromal nodules (20a). After an ophthalmic evaluation, a corneal cytology sample was collected with the back end of a No. 15 Bard-Parker scalpel (20b). 20a
1 What would be the differential diagnoses based on the clinical presentation? 2 What is your diagnosis based on the corneal cytology? 3 What additional diagnostics and treatment would you pursue in this case?
CASE 21 An 8-year-old blue and gold macaw (Ara ararauna) is presented for an overgrown beak (21). The condition has been evolving for years. Physical examination of the bird shows a severe overgrown rhinotheca in length and thickness. 21
1 What additional examination could you perform to assess the thickness of the overgrown keratin layer? 2 How would you treat this condition? 3 What pathologies may result in excessive beak growth in psittacine birds?
Questions CASE 22 A 17-year-old male Timneh African
22 grey parrot (Psittacus erithacus timneh) was presented on emergency for seizure episodes. When the owner returned from work on the night of presentation, the bird was at the bottom of the cage standing strangely (22). He was able to step up, but when the owner put him back in the cage, he began seizing in the cage and this occurred again outside on the floor. During these episodes, his eyes were open, his wings and right pelvic limb shook, and he leaned over. When the bird recovered, he appeared to have right-sided weakness and knuckling of the right foot with decreased gripping. The bird was fed a balanced pelleted diet and had lived indoors without being exposed to other birds for all his life. The neurologic examination revealed a quiet but responsive bird, ataxic, and weak on the right foot. Menace was absent in the right eye, with decreased vision. Proprioceptive deficits were absent in the right leg. The ophthalmic examination was unremarkable other than partial vision loss in the right eye. CBC and biochemistry panel were normal apart from a stress leukogram and moderate elevation of cholesterol and LDL. Radiographs showed increased opacity of great vessels of the heart. A heavy metal panel was negative for lead, zinc, and copper.
1 What is the most likely diagnosis? 2 What additional test would you perform to confirm your diagnosis? 3 How would you treat this bird?
CASE 23 A new client requests a wellness examination for his female (DNAsexed) Hispaniolan Amazon parrot (Amazona ventralis). The bird’s current diet is composed of a combination of sunflower seeds, bananas, corn, broccoli, strawberries, commercial pellets formulated for psittacines, and peanut butter as a treat. The owner estimates that the commercial pellets comprise about 20–25% of the bird’s daily intake. 1 What is your assessment of this diet? 2 What are the potential nutritional deficiencies that psittacines fed such a diet may be presented with? How would they manifest clinically? 3 What would be your recommendation in terms of this bird’s diet?
CASE 24 Two radiographic images (24a, b) were obtained from a wild adult male barred owl (Strix varia) found on the ground unable to fly. Apoorly defined soft tissue opacity can be seen in the area of the right thoracic inlet. 24a
1 Describe the normal anatomic structures that can be found in the area of the soft tissue structure, taking into consideration both radiographic views. List five differential diagnoses for the soft tissue structure seen in the radiographs. 2 What other diagnostic tests should be considered to further evaluate the nature and identity of the soft tissue structure seen on the image? 3 If the mass affects the thyroid gland, what is the most likely diagnosis?
CASE 25 A saker falcon (25a) (Falco cherrug) and a raven (25b) (Corvus corax) are each presented for evaluation with digital lesions of unknown duration. 25a
1 What disease is demonstrated in each image? 2 What is the etiology? 3 What treatment and preventive actions should be taken? 14
Questions CASE 26 A 4-year-old galah cockatoo (Eolophus roseicapilla) is referred to you. The referring veterinarian initially saw the bird when it was fluffed up and anorexic, with increased green coloration in the urates. Supportive therapy was provided and antibiotic, antifungal, and NSAID treatment was commenced. The patient initially improved, but never 26a returned to its former self. Blood testing was carried out a month later; hematologic parameters were within reference values except for an elevated hematocrit of 58%. Biochemistry indicated elevated AST and GLDH and normal CK and bile acid. All other parameters were within reference values. In subsequent weeks, the owners noted marked exercise intolerance and the bird was referred for further diagnostic tests. The CBC and plasma biochemistry panel were repeated. The hematocrit had increased to 61%, all other parameters had normalized. Radiographs were taken (26a, b). In the lateral view, the heart length is 2.83 cm and the sternal length is 4.79 cm, while on the ventrodorsal view the heart width is 2.11 cm and the thorax width is 3.49 cm. Using those measurements, the heart is 60% of the chest width and the heart length is 44% of the sternal length. 26b
1 What are the abnormal radiographic findings? 2 How do these findings explain the clinical pathology finding? 3 What further diagnostic tests might be beneficial? 15
CASE 27 Two 2-year-old barred Plymouth rock hens (Gallus gallus domesticus) presenting with a 2-day history of progressively worsening respiratory disease consisting of varying degrees of mild serous nasal discharge, rales, mild coughing, periorbital swelling, and edema of 27 the head are shown (27). These hens and about 20 others of the same age had been purchased as a group 6 days previously from a private breeder. At presentation approximately half the birds had died showing similar signs, and some hens also had laid eggs with irregular shells. The owner brought these two for euthanasia and testing. 1 What diseases could cause these clinical signs? Which one is most likely? 2 How would you euthanize these birds? 3 What diagnostic test would you perform?
CASE 28 Radiowave radiosurgical instruments (28) use electron waves at a specific radiofrequency to cause ionic agitation in the cells at the tip of the electrode when the electrode is in contact with tissue, resulting in heating of the tissue with vaporization of tissue fluid, thus causing incision and coagulation. This heat causes collagen denaturation and tissue shrinkage with thrombosis of associated blood vessels, which manifests as improved incisional hemostasis. 28
1 List the five principal factors that control the amount of lateral heat damage occurring in a radiosurgical incision. 2 What are the advantages of bipolar over monopolar radiosurgery? 3 What special considerations occur during the preparation of a potential surgical field if radiosurgery is to be used?
Questions CASE 29 A 5-month-old African grey parrot (Psittacus erithacus) presents because of lethargy, decrease vocalization and inappetence. The bird was mildly dehydrated but otherwise the physical examination was fairly unremarkable. During the physical examination, the bird passed bright yellow urates. Hematologic findings indicated that the bird had a moderate anemia that appeared nonregenerative and severe leukopenia with absence of heterophils. Erythrocyte parameters Red blood cells Hematocrit Mean corpuscular volume
Result 2.11 M/µL (2.11 × 1012/L) 29% (0.29 L/L) 137.4 fl
Red blood cell morphology Anisocytosis
Leukocyte parameters White blood cells Neutrophils Lymphocytes Monocytes Eosinophils Basophils
1,400/µL (1.4 × 109/L) 0/µL (0 × 109/L) 1,176/µL (1.176 × 109/L) 224/µL (0.224 × 109/L) 0/µL (0 × 109/L) 0/µL (0 × 109/L)
Other parameters Plasma protein Plasma fibrinogen Protein:fibrinogen ratio
3.2 g/dL (32 g/L) 200 mg/dL (5.88 µmol/L) 15
1 What is the most likely diagnosis? 2 What additional test would you perform to confirm your diagnosis? 3 How would you treat this disease? What is the prognosis?
1 What is Hexamita meleagridis (Spironucleus meleagridis)? 2 What are the clinical signs observed in partridges and pheasants, and why do these signs occur?
3 How is this disease diagnosed and controlled?
CASE 31 A domestic egg laying hen (Gallus gallus domesticus) is presented for evaluation of lack of egg production despite broody behavior. The owner reported that the bird is also eating less, appears thin, and has a distended but firm coelom, both of which you confirm during your physical examination. Two ultrasound images are shown (31a, dorsocaudal coelom; 31b, dorsal mid-coelom just cranial to 31a). 31a
1 Based on the physical examination findings and the features of the ultrasound images, what is the cause of the coelomic distension in this hen? 2 What is the proposed pathophysiology of this condition in laying hens? 3 Describe the treatment options (medical and/or surgical) for this case.
CASE 32 A red-breasted toucan (Ramphastos dicolorus) was found severely depressed on the floor of its aviary, with fluffed feathers. Supportive care and enrofloxacin were administered but the 32a bird was found dead soon afterwards. At gross necropsy the bird showed severely hemorrhagic lungs (32a) and several other organs were congested with petechiae. 1 What are your main differential diagnoses? 2 How would you confirm them? 3 How would you treat this condition?
Questions CASE 33 An adult Hispaniolan Amazon parrot (Amazona ventralis) is being manually restrained in a towel for induction of anesthesia, prior to diagnostic work up. Isoflurane is delivered in oxygen via a facemask tightly fitting around the bird’s face to decrease exposure of personnel to anesthetic gas (33).
1 How long should avian patients be fasted prior to anesthesia? 2 What preanesthetic evaluation should be considered? 3 What premedication may be considered?
CASE 34 A saker falcon (Falco
34 cherrug) was presented with a history of progressive weight loss and reduced appetite. The owner reported that for the past week the falcon had been trying to eat but appeared to have difficulty tearing and swallowing its food. On examination the tongue was found to be significantly enlarged, containing numerous white caseous foci on its dorsal and lateral aspects. Similar caseous foci were also seen on the hard palate (34). Abundant clear mucus could be observed on the choana and under the tongue. Food remains were plastered on both sides of the upper and lower beaks. 1 Based on the history and clinical findings described, list three significant differential diagnoses. 2 What diagnostic tests would you perform to confirm the diagnosis? 3 Microbiological cultures yielded pure growths of Pseudomonas aeruginosa, which were suspected to have occurred subsequent to a prior Trichomonas infection. What therapeutic management would you establish for the Pseudomonas spp. infection?
CASE 35 An adult female peregrine falcon (Falco peregrinus) was presented to a veterinary clinic for general examination with a history of anorexia for the past 2 days and the passing of green stained urates. The falcon was imported into the country as a juvenile (500 g) may be fasted for 12 hours or longer in some cases. Water is offered up to 2–3 hours before induction. The aim is to avoid anesthetizing any bird that does not have an empty crop, except in emergency situations. Birds with significant crop content may require their crop to be emptied using a gavage tube. Otherwise, the head should be kept elevated above the crop during induction and intubation, and packing of the pharynx should be performed.
2 What preanesthetic evaluation should be considered? Prior to anesthesia, a comprehensive history and a complete physical examination should be conducted. Initial assessment should focus on evaluating the cardiopulmonary function (mucous membranes, vein refill time, auscultation, respiratory rate), body condition, and hydration status. As a generalization, the minimal clinicopathologic database includes PCV, total protein, and blood glucose. CBC, chemistry panel, and other tests are performed according to the bird’s condition. Each patient should be considered individually and the clinical approach should be adjusted accordingly. 3 What premedication may be considered? Depending on the procedure anticipated, prior to gas induction, analgesia may be provided with butorphanol. Butorphanol has been shown to lower the minimum anesthetic concentration (MAC) in some parrot species. Benzodiazepines produce dose-dependent sedative-hypnosis and muscle relaxation. They are used as anxiolytics to facilitate induction and for minor nonpainful procedures. Midazolam may be administered (0.1–1 mg/kg SC or IM) for sedative purposes. Midazolam given IN (0.5–2 mg/kg) provides fast and reliable sedation in budgerigars. In Hispaniolan Amazon parrots, administration of midazolam IN yields sedative effects within 3 minutes of administration, with vocalization, flight, and defense responses significantly reduced during capture. If surgery or procedures involving the head, eyes, or neck of the patient are anticipated, glycopyrrolate (0.01 mg/kg SC, IM, or IV) or atropine (0.02–0.08 mg/kg SC, IM or IV) is advised in order to prevent vagal induced bradycardia. Further reading Heard DJ (2000) Avian anesthesia. In: Manual of Avian Medicine. (eds. GH Olsen, SE Orsoz) Mosby, St. Louis, pp. 464–492. Mans C, Guzman DS, Lahner LL et al. (2012) Sedation and physiologic response to manual restraint after intranasal administration of midazolam in Hispaniolan Amazon parrots (Amazona ventralis). J Avian Med Surg 26(3):130–139. Sadeg AB (2013) Comparison of intranasal administration of xylazine, diazepam, and midazolam in budgerigars (Melopsittacus undulatus): clinical evaluation. J Zoo Wildlife Med 44(2):241–244.
CASE 34 1 Based on the history and clinical findings described, list three significant differential diagnoses. (1) Pseudomoniasis, caused by Pseudomonas aeruginosa; (2) trichomoniasis, caused by Trichomonas gallinae; (3) candidiasis, most likely caused by Candida albicans.
Answers 2 What diagnostic tests would you perform to confirm the diagnosis? (1) Stain wet smears obtained from the oropharynx using a rapid stain (e.g. Diff-Quik™), methylene blue stain, or Giemsa stain. (2) Bacterial and fungal culture. 3 Microbiological cultures yielded pure growths of Pseudomonas aeruginosa, which were suspected to have occurred subsequent to a prior Trichomonas infection. What therapeutic management would you establish for the Pseudomonas spp. infection? Provide nutritional support by gavage feeding two or three times a day as necessary in order to maintain or gain weight. Based on the sensitivity test, the antibiotics recommended included piperacillin (100 mg/kg q12h) on its own or in combination with tobramycin (10 mg/kg IM q12h for 7–10 days). Débride the caseous masses and spray the oropharynx with a 1% povidone–iodine mouthwash preparation. In birds with unilateral or bilateral sinusitis, use a solution of chlorhexidine (0.2 ml of a 5% preparation diluted to 20 ml with sterile saline) or F10 (Health and Hygiene) (1:250) to flush the affected sinus q12h for 3–5 days. Further reading Samour J (2000) Pseudomonas aeruginosa stomatitis as a sequel to trichomoniasis in captive saker falcons (Falco cherrug). J Avian Med Surg 14(2):113–117.
CASE 35 1 What common diseases could produce anorexia and the passing of green urates in falcons? Columbid herpesvirus 1, lead toxicosis, amyloidosis, Escherichia coli septicemia, aspergillosis. 2 What laboratory diagnostic tests you would require to establish a definitive diagnosis? Essential testing includes hematology, blood chemistry, and survey radiographs. Additional testing includes endoscopy and liver biopsy together with histopathology, microbiology, PCR testing, and serology testing. 3 How would you proceed in the light of these findings? Avian influenza is an infectious disease transmitted by a virus of the family Orthomyxoviridae and is a notifiable disease. Avian influenza virus phenotypes H5, H7, and H9 represent a high pandemic potential. The relevant authorities should be notified of the findings. The virus is commonly transmitted through direct contact with feces and aerosols from infected birds and through contaminated water in overcrowded ponds and lakes. Adequate disinfection of the premises where the falcon was examined and housed overnight should be undertaken. Further reading Samour J,Naldo JL, Wernery U et al. (2007) Avian influenza infection in saker falcons (Falco cherrug).ProcEurop Assoc Avian Vet Conf, Zurich, pp. 155–162.
CASE 36 1 What is the most likely cause for the elevated AST in this patient? AST is found in both the liver and muscle, as well as in red blood cells. Therefore, elevations in this parameter could correlate with disease in either system. With the severe elevation in CK, which is only found in muscle, the AST elevation is most consistent with recent muscle damage due to trauma from the dog bite. In birds, the halflife of AST is twice as long as the half-life of CK, which is also longer than in LDH. Therefore, depending on the time interval between muscle injury and blood collection, the CK may have returned to normal while the AST is still elevated. 2 Can liver disease be ruled out as a cause for the elevated AST? What other values could be tested to rule in or out liver disease? Liver disease cannot be ruled out as the bird could have concurrent muscle and liver damage. Blood should also be collected to look at other liver parameters such as bile acids, which will give additional information on liver function. However, it is common to have active liver cellular damage prior to any effect on liver function (bile acid). Other liver values such as GGT could be measured, although GGT is not a very sensitive indicator of liver disease. A very sensitive indicator of liver injury, LDH would not be helpful to differentiate between liver and muscle damage, as LDH is found in liver and muscle and also the half-life is too short to be of significant value. 3 Apart from muscle trauma such as a dog bite, in what other situations is it common to see elevated CK levels in avian patients? CK concentrations will also be elevated following IM injections and in situations where a patient is losing body mass (e.g. weight reduction due to muscle breakdown). Further reading Fudge AM (2000) Laboratory reference ranges for selected avian, mammalian, and reptilian species. In: Laboratory Medicine Avian and Exotic Pets. (ed. AM Fudge) WB Saunders, Philadelphia, pp. 375–400. Lumeij JT, De Bruijne JJ, Slob A et al. (1988) Enzyme activities in tissues and elimination half-lives of homologous muscle and liver enzymes in the racing pigeon (Columba livia domestica).Avian Pathol17(4):851–864. Lumeij JT, Meidam M, Wolfswinkel J et al. (1998) Changes in plasma chemistry after druginduced liver disease or muscle necrosis in racing pigeons (Columba livia domestica). Avian Pathol 17(4):865–874.
CASE 37 1 Which species of Aspergillus are causative agents of respiratory aspergillosis in psittacine birds? What is the commonest source of infection? Aspergillus fumigatus, A. flavus, A. niger, A. terreus. The commonest source of infection in parrots is contaminated seed-based diets that have been harvested or stored with a moisture content of >17%. Seed batches with weevil contamination are at particular risk.
Answers The weevil lays eggs in the sunflower seed. When the egg hatches, the weevil beetle bores its way out of the seed, leaving a hole for moisture to enter and create a suitable environment for Aspergillus spp. spores to develop. 2 How you would treat a psittacine bird with respiratory aspergillosis? What should be considered regarding the different drugs? Combination therapy using systemic and topical or nebulized agents is beneficial for the treatment of aspergillosis. Administration of amphotericin B is advised initially as an IV bolus, due to its rapid fungicidal effect, but care should be taken in dehydrated patients or those with pre-existing renal disease as amphotericin B is potentially nephrotoxic. Further systemic therapy options include agents of the azole family (e.g. voriconazole, itraconazole). The modern avian licensed itraconazole formulation (Fungitraxx®, Petlife International) has a far superior respiratory tissue level compared with the human version previously used in birds. Systemic drugs may be used in conjunction with topical nebulizable agents such as F10 (Health and Hygiene) or enilconazole (Imaverol: Elanco) delivered 3–4 times daily for periods of 15–20 minutes. Direct application of antifungal drugs such as clotrimazole, enilconazole, or F10 to endoscopically visualized fungal plaques is also beneficial in controlling lesions. As aspergillosis often occurs in birds with immunosuppression, environmental conditions should always be improved as well (housing, nutrition, treatment of concurrent diseases, air hygiene). 3 Which antifungal drug has been shown to cause adverse reactions in African grey parrots suffering from aspergillosis? Which alternate systemic antifungal drugs may be used for aspergillosis in these birds? The first-generation triazole itraconazole has been shown to be poorly tolerated in some psittacine birds and may be toxic in affected species. The second-generation triazole voriconazole (VFend®, Pfizer) and the allylamine drug terbinafine hydrochloride may be used in sensitive patients (e.g. African grey parrots) and seem to be well tolerated. Further reading Girling SJ (2005) Respiratory disease. In: BSAVA Manual of Psittacine Birds, 2nd edn. (eds. N Harcourt-Brown, J Chitty) British Small Animal Veterinary Association, Gloucester, pp. 170–179.
CASE 38 1 What would be included in your differential diagnoses for this case? Differential diagnoses for chronic regurgitation and crop enlargement include infectious diseases affecting the upper gastrointestinal system, gastrointestinal foreign bodies, traumatic injuries or burns, heavy metal toxicity, neoplasia, or crop stasis as a result of metabolic and systemic conditions such as dehydration or renal disease. Increased respiratory effort that is mostly expressed in inspiration indicates upper
respiratory tract disorders. Differentials for this include infectious diseases of the trachea or the nasal cavity, mechanical obstruction by foreign material, exposure to irritating substances (such as smoke or aerosols), trauma, stricture of the trachea or nares, granuloma, and neoplasia. Mechanical tracheal compression may result from enlargement of the thyroid gland. Thyroid goiter of a nutritional etiology is the most common thyroid pathology in birds, and has been described primarily in budgerigars. Budgerigars with goiter usually do not present with clinical signs of hypothyroidism; presentation is rather a progressive dyspnea, commencing with a clicking noise as the bird breathes. 2 What diagnostic tests could be of aid in diagnosis? Radiographs may demonstrate compression and even displacement of the trachea by a soft tissue mass. Due to lack of specific diagnostic tests, diagnosis of goiter relies on clinical signs, diet history, and presentation. Budgerigars suffering from goiter do not have clinical signs or changes in thyroid levels characteristic of hypothyroidism, therefore there would be little use for a thyroid hormone panel. 3 What would be included in your treatment plan? This bird presented with increased respiratory effort and might benefit from oxygen until stabilized. Longterm supplementation of iodine solution, such as Lugol’s iodine (1 drop of 0.3% Lugol solution per 20 mL of water daily for the first week, three times a week for the second week, then weekly), may be used to restore iodine status, which will lead to a decrease in the thyroid size and resolution of clinical signs. A conversion to a diet based on at least 75% commercial formulated pellets is recommended to decrease the risk of concurrent nutritional deficiencies. Further reading Merryman JI, Buckles EL (1998) The avian thyroid gland. Part two: a review of function and pathophysiology. J Avian Med Surg 12:238–242.
CASE 39 1 Describe the radiographic findings. What should the radiographic size for the heart be in medium to large-size parrots? What is the radiographic appearance of the heart in cockatoos? There is a severe enlargement of the cardiac silhouette visible on both the ventrodorsal and lateral views. There is no evidence of ascites and the pulmonary field appears clear or with a slight parabronchial pattern (honeycomb appearance more marked). In medium to large-size Psittaciformes, the radiographic cardiac size on a ventrodorsal radiographic view should comprise 51–61% of the thoracic width at its widest point. This may be slightly affected by respiratory stage at the time of obtaining the radiographs. In large cockatoos, an air sac diverticulum from the interclavicular air sac is seen between the heart and the sternum, which is visible on a lateral radiographic view. In this cockatoo,
Answers the air space between the heart and the sternum is diminished and the heart is in contact with the sternum, which is abnormal for the species. 2 Describe the echocardiographic findings. What do you know about the reliability of echocardiographic measurements in birds? What is the differential diagnosis for these findings? What is the likely cause for the respiratory signs? There is a severely enlarged left atrium and mild pericardial effusion. The ventricles are considered to be of normal size. On the color Doppler images (not shown), there was a large amount of turbulence at the left atrioventricular valve. Together, these changes may be caused by left atrioventricular insufficiency or stenosis. The most likely cause for the dyspnea noted at presentation would be pulmonary edema or decreased cardiac output. The bird was eventually euthanized and necropsy confirmed the presence of left atrioventricular stenosis and pulmonary edema. Echocardiographic measurements in birds have been shown to be of low reliability overall with low interobserver agreement. This is due to the small structures imaged and the fast heart rate. Consequently, published reference values should be used with caution. 3 What other clinical signs are common in companion psittacine birds with this condition? In pet birds, right heart or bilateral heart failure is typically common and classically manifests with exercise intolerance, ascites, hepatic congestion, pericardial effusion, dyspnea from air sac compression, and valvular insufficiency. Further reading Beaufrere H, Pariaut R, Rodriguez D et al. (2012) Comparison of transcoelomic, contrast transcoelomic, and transesophageal echocardiography in anesthetized red-tailed hawk (Buteo jamaicensis). Am J Vet Res 73(10):1560–1568. Krautwald-Junghanns M-E, Pees M, Schroff S (2011) Cardiovascular system. In: Diagnostic Imaging of Exotic Pets. (eds. M-E Krautwald-Junghanns, M. Pees, S. Reese, T. Tully) Schlutersche Verlagsgesellschaft mbH & Co., Hanover, pp. 84–91. Pees M, Krautwald-Junghanns M-E (2009) Cardiovascular physiology and diseases of pet birds. Vet Clin North Am Exot Anim Pract 12(1):81–97.
CASE 40 1 What is your presumptive diagnosis? Protozoal enteritis, possibly due to Giardia spp. Several typical flagellate trophozoites and cysts can be observed in the fecal cytology. Budding yeasts are also apparent. 2 What additional examination would you request? PCR testing of the stools confirmed the diagnosis of giardiasis. Acomplete blood panel would help to assess the overall clinical condition of the bird and, more importantly, the severity of the anemia due to the blood loss.
3 How would you treat this condition? This condition should be treated with metronidazole (50 mg/kg PO q12h for 5 days) and supportive therapy. In severe cases of anemia (PCV 10 mm Hg after a resuscitation time of 15–20 minutes, the resuscitative effort may be ineffective. Further reading Acierno MJ, da Cunha A, Smith J et al. (2008) Agreement between direct and indirect blood pressure measurements obtained from anesthetized Hispaniolan Amazon parrots. J Am Vet Med Assoc 233(10):1587–1590. Schnellbacher RW, da Cunha AF, Beaufrère H et al. (2012) Effects of dopamine and dobutamine on isoflurane-induced hypotension in Hispaniolan Amazon parrots (Amazona ventralis). Am J Vet Res 73(7):952–958. Zehnder AM, Hawkins MG, Pascoe PJ et al. (2009) Evaluation of indirect blood pressure monitoring in awake and anesthetized red-tailed hawks (Buteo jamaicensis): effects of cuff size, cuff placement, and monitoring equipment. Vet Anaesth Analg 36(5):464–479.
CASE 89 1 When giving IM injections, which portion of the pectorals should be avoided, and why? Avoid the cranial (especially lateral) portion of the pectoral muscles to prevent inadvertent injection into vasculature located in this region. 2 Why are the leg muscles generally not recommended for IM injections in birds? Drugs injected into the leg muscles may be excreted by the kidneys through the renal portal system before reaching the systemic circulation. The injection of nephrotoxic drugs into the legs is particularly dangerous and contraindicated. There is also a greater risk of causing neural damage when injecting into poorly muscled legs, compared with the pectoral muscles.
3 Vascular access can be challenging in small and hypotense patients and in these cases IO access for fluid therapy may be necessary. Where are IO injections most commonly delivered? IO injections are most commonly delivered into the distal ulna or proximal tibia using a 22- to 25-gauge hypodermic or spinal needle in most species. Because of the presence of some pneumatized bones that communicate with the respiratory system in most species (e.g. femur and humerus), IO catheters should be avoided in these locations. Further reading Powers L (2006) Common procedures in psittacines. Vet Clin North Am Exotic Anim Pract 9(2):293–294, 287, 301–302.
CASE 90 1 Which laboratory diagnostic test offers the highest correlation with disease? The diagnostic test with the highest laboratory correlation with PBFD is the presence of high virus antigen titers shed from feathers, which is measurable by hemagglutination activity (HA). The diagnosis of PBFD requires the observation of clinical or histopathologic lesions, which includes feather dystrophy, feather loss, and basophilic intracytoplasmic inclusions. When clinical signs of feather disease are present, supportive diagnostic tests such as PCR assays are useful for assisting clinicians with making a diagnosis, but PCR tests may detect viral DNA in birds that are clinically normal, subclinically infected, and/or recovering from infection. The best sample for PCR testing is blood since this minimizes the potential for environmental contamination, a risk if feathers were collected for testing instead. Many clinically normal birds can be PCR positive for many months as they mount an effective immune response. While most birds with high serum antibody concentrations are free from the disease, some birds and individual bird species can also be antibody positive. 2 How many different genotypes of BFDV exist? All psittacine bird species are susceptible to BFDV, which is considered a single virus species with little if any antigenic variation. However, there is great genetic diversity with numerous studies demonstrating quasi-species genetic variation of BFDV within individually infected birds. This genetic variation has implications for the sensitivity and specificity of individual diagnostic PCR tests. Assay protocols should be targeted to the most conserved regions of the BFDV genome, but even then a very small percentage of BFDV genotypes may not be detected by an individual PCR test. PCR tests that target small regions of the genome tend to be the most sensitive for detecting viral DNA but with less discrimination of active viral replication. PCR tests that target larger sections of the genome have a stronger correlation with active virus replication and shedding.
Answers 3 Would genetic variation in BFDV interfere with diagnostic testing? Ideally, at least two methods of detection should be used to validate test results. This could be through combined viral DNA testing (PCR) and antigen detection or by targeting two regions of the virus genome with different PCR tests. BFDV is a single-stranded DNA virus that replicates autonomously in the nucleus of infected cells where it relies on host DNA replication machinery; it does not insert itself into the host genome. Further reading Khalesi B, Bonne NJ, Stewart M et al. (2005) A comparison of haemagglutination (HA), haemagglutination inhibition (HI) and PCR for the detection of psittacine beak and feather disease virus (BFDV) infection and a comparison of isolates obtained from Loriids. J Gen Virol 86:3039–3046.
CASE 91 1 What species are these chicks? Are they precocial or altricial? These neonatal ratite chicks are cassowaries (Casuarius spp.). They are precocial, hatched with eyes open, feathers, and able to walk, run, forage, and hunt soon after hatch. 2 These chicks will be raised by their paternal parent. Why is this? These newly hatched ratite chicks will be raised by their paternal parent, as their maternal parent is polyandrous. Polyandrous cassowary females mate with up to four males per breeding season. Once the female cassowary lays her eggs she is chased away from her nest by her mate. She then goes off to find another mate. The paternal parent incubates the eggs and raises the chicks. 3 How and what does their paternal parent feed them? The paternal cassowary parent feeds the chicks by teaching them to forage for fruit (berries) and hunt for small prey (small insects and eventually reptiles, rodents, carrion and fish) and by coprophagia. Precocial cassowary chicks are omnivores and predominately frugivores. Further reading Romagnano A, Glenn Hood R, Snedeker S et al. (2012) Cassowary pediatrics. Vet Clin North Am Exot Anim Pract15(2):215–231.
CASE 92 1 Which bone is repaired first? The radius. 2 What additional method of surgical stabilization could be added to reduce the oblique ulnar fracture and increase resistance to the distractive force of the triceps muscle? Hemicerclage wire could be used to tie down the oblique
ends of the fracture; in this case a k-wire/figure-of-eight wire combo was used (92c). During open surgery, a k-wire pin (0.035 in) was driven perpendicularly through the oblique bone fragments. Cerclage wire was then wrapped in a figureof-eight pattern around the pin and tightened (92d). The ends of the k-wire were then cut prior to closure of the skin and soft tissues. Cerclage should only be used in conjunction with other fixation methods and never by itself when repairing fractures. Circumferential cerclage can cause tissue necrosis and other complications in avian patients, and therefore should be used cautiously. Further reading Redig PT, Ponder J (2016) Orthopedic surgery. In: Avian Medicine, 3rd edn. (ed. J Samour) Mosby, St. Louis, pp. 312–350.
CASE 93 1 How would you describe this gross lesion, and what is the most likely cause for it? The brachiocephalic arterial wall is thickened with yellowish discoloration and apparent decreased luminal diameter. This gross lesion is typical for atherosclerosis. 2 What are the histopathologic hallmarks of these types of lesions, and what are the different lesion types that have been described? Histopathology is characterized by the infiltration of fat, foamy macrophages, necrotic materials, and increased extracellular matrix in the subintimal and medial layers of the artery, causing the formation of a necrotic atheromatous core. The atheromatous lesion is frequently calcified with chondroid formation. The lesions may also contain a large amount
Answers of collagen (fibrosis). The dense collagen material covering a fibroatheromatous lesion is called the fibrous cap. Lesions may be complicated by hemorrhage, thrombosis, and fissures, but these are uncommon in birds. Advanced lesions tend to cause drastic disruption in arterial anatomy with significant arterial luminal stenosis. In birds, clinical signs are more often attributed to ‘flow-limiting stenosis’ rather than atherothrombosis and emboli, as seen in humans. Atheromatous lesions are classified in seven lesion types: pre-atheromatous lesions (I: scattered foamy macrophages with mild increase in extracellular matrix; II: sheets of foamy macrophages and small pools of extracellular lipid); intermediate lesions (III: larger coalescent fatty deposition starting to disrupt arterial architecture); advanced lesions (IV: large lipid area forming a lipidonecrotic core = atheroma; V:increased presence of fibromuscular tissue forming a fibrous cap over the lipid core = fibroatheromas); complicated lesions (VI: hematoma, emboli, and fissures); and predominantly calcific lesions (VII). 3 What risk factors associated with the development of these types of lesions were present in this bird? This bird had several risk factors, namely its species, gender, and advanced age. Psittacine species predisposed to atherosclerosis are African grey parrots (Psittacus erithacus), Amazon parrots (Amazona spp.), cockatiels (Nymphicus hollandicus), and quaker parrots (Myiopsitta monachus). In contrast to mammals, female birds are more prone to atherosclerosis than males. Age is also a significant risk factor; psittacine birds aged over 20–30 have aprobability >30% of having a severe atherosclerotic lesion. Chronic reproductive activity is another risk factor that was identified in an epidemiologic survey. While it has not been conclusively demonstrated, other risk factors are expected to occur and include dyslipidemia (e.g. high blood cholesterol), inadequate diet, and lack of activity. Further reading
Beaufrère H (2013) Avian atherosclerosis: parrots and beyond. J Exot Pet Med 22(4):336– 347. Beaufrère H, Ammersbach M, Reavill DR et al. (2013) Prevalence of and risk factors associated with atherosclerosis in psittacine birds. J Am Vet Med Assoc 242(12):1696– 1704. Beaufrère H, Nevarez JG, Holder K et al. (2011) Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy. Avian Pathol 40(5):531–544. Beaufrère H, Pariaut R, Rodriguez D et al. (2010) Avian vascular imaging: a review. J Avian Med Surg 24(3):174–184. Beaufrère H, Rodriguez D, Pariaut R et al. (2011) Estimation of intrathoracic arterial diameter by means of computed tomographic angiography in Hispaniolan Amazon parrots. Am J Vet Res 72(2):210–218.
CASE 94 1 What are the treatment options? Masterly inactivity and hope for the best; however, the natural method of feeding by a raptor (i.e. holding food between the talons and pulling at it with the beak) would be anticipated to result in further instability and spinal cord damage. Alternatively, one could consider external splinting, but if this were a padded neck support, the cranial extremity would be close to the fracture site and actually increase the risk. 2 If external support is to be provided, how can this be achieved? Effective external support of the fracture can only be provided if the head can also be immobilized. This can be achieved with a transfrontal sinus pin, linked to the external cervical support (94b). 94b
3 If an external support is provided, how should the bird be fed? Feeding during recovery can be achieved using an esophagostomy feeding tube, placed via the proximal crop into the proventriculus and administering a carnivore critical care diet that will pass via such a tube. The support and pin were removed from this case after 3 weeks and the bird made an uneventful and full recovery. Further reading Forbes NA (2015) Recent advances in raptor orthopaedic surgery. In: Proceedings British Veterinary Zoological Society Spring Meeting, Loughborough. Huynh M, Sabater M, Brandão J et al. (2014) Use of an esophagostomy tube as a method of nutritional management in raptors: a case series. J Avian Med Surg 28(1):24–30.
CASE 95 1 What surgical procedure would you perform to resolve this condition? Tracheal resection and anastomosis. 2 How would you perform this procedure? Tracheal surgery requires prior air sac intubation to maintain anesthesia. The bird is positioned in dorsal recumbency.
Answers The skin is incised along the ventral midline of the neck or just lateral to the crop. The subcutaneous tissues are dissected to reveal the paired sternothyroideus muscles. The recurrent nerves are identified and avoided. A tracheal ring cranial and caudal to the affected segment is bisected circumferentially with a No. 11 scalpel blade. The tracheal ends are approximated by preplacing simple interrupted sutures of 4-0 to 6-0 polydioxanone on a tapered needle. The sutures are tightened individually with extraluminal knots to appose the tracheal ends. The sternohyoid muscles are apposed over the ventral aspect of the trachea. The thoracic inlet must be closed (air tight) by reattaching the crop/esophagus. The skin closure is routine. In any avian patient it is possible to safely remove six tracheal rings, while in some additional rings may also be removed. In cases with extended areas of damage, an alternative treatment option is the placement of a Teflon stent within the tracheal lumen. Such stents are commercially available for diameters of 4 mm and upwards. 3 What postoperative complications might occur? Damage to the recurrent nerves might result from surgical manipulation or radical resection. The recurrent nerve does not innervate the larynx in birds but instead innervates the esophagus, crop and the tracheal and syringeal muscles; thus, damage to the recurrent nerves will not cause laryngeal paralysis but might instead cause a change in voice. The larynx in birds is innervated by the glossopharyngeal nerve. Postsurgical tracheal stenosis is another possible postoperative complication and efforts should be made to minimize anastomotic stenosis by near-perfect apposition of the anastomosis site, minimally reactive suture material, applying appropriate suture technique, and reducing tension at the surgical site if needed with tension-relieving sutures, each encircling a tracheal cartilage proximal and distal to the anastomosis site. Further reading Guzman DS, Mitchell M, Hedlund CS et al. (2007) Tracheal resection and anastomosis in a mallard duck (Anas platyrhynchos) with traumatic segmental tracheal collapse. J Avian Med Surg 21(2):150–157.
CASE 96 1 What are your differential diagnoses? Differential diagnoses would include fungal infection, trauma, neoplasia, and psittacine beak and feather disease (PBFD) caused by psittacine circovirus. The bird is suffering from a fungal infection of the keratin layer, which over time has resulted in a severe malformation and deviation with cracking of the beak. 2 What diagnostic tests would you carry out to confirm your diagnosis? Hematology and biochemistry panel may be useful to exclude any other metabolic diseases. Radiographs would provide some information on the extent of a possible infection to rule out involvement of the mandible. Biopsy for histopathology
and bacterial and fungal culture of flaky beak material is essential. PBFD, while unlikely, could be tested by PCR for circovirus from a blood sample or feather pulp material. 3 What treatment would you recommend, and for how long should it be maintained? Systemic and possibly topical antifungal therapy is essential and will need to be maintained for at least 2 weeks after the beak appears normal, which might require 8–12 weeks. Further reading Cooper JE, Harrison GJ (1994) Dermatology. In: Avian Medicine: Principles and Applications. (eds. BW Ritchie, GJ Harrison, LJ Harrison) Winger’s Publications, Lake Worth, pp. 607–639.
CASE 97 1 How does end-tidal partial pressure of carbon dioxide (PETCO2) correlate with partial arterial pressure of carbon dioxide (PaCO2) in psittacine birds? Results of studies in African grey parrots indicate that PETCO2 reliably estimates PaCO2 in isoflurane anesthetized birds receiving intermittent positive-pressure ventilation (IPPV) and suggest that IPPV combined with capnography is a viable option for anesthetic maintenance in avian patients. PETCO2 overestimated PaCO2 by approximately 5 mmHg, which is the opposite of what is seen in mammals. PETCO2 exceeds PaCO2 in birds secondary to the parabronchial cross-current gas exchange mechanism. PaCO2 in awake birds ranges from approximately 25 to 40 mm Hg. PETCO2 of 30–45 mm Hg is considered appropriate for isoflurane anesthetized patients. 2 How do pulse oximetry values correlate with heart rates and arterial oxygen saturation (SaO2)? Pulse oximetry is accurate in estimating heart rates. However, the pulse oximeter underestimates the actual SaO2 in birds. Despite the poor accuracy of reported values, trends in oxygenation are apparent and valuable. Motion artifact and the fact that calibration uses the human hemoglobin dissociation curve are the most important factors that interfere with the accuracy of avian measurements. With inhalant anesthesia, arterial partial pressure of oxygen is high because of the high fraction of inspired oxygen delivered; furthermore, respiratory problems are difficult to detect without assessing the arterial blood gases. 3 Doppler has been used in avian anesthesia for indirect blood pressure measurements. What were the conclusions of those studies? Studies showed blood pressure measurements varied significantly between cuff placements on the same limb from the same bird and between individual birds. The precision of these indirect blood pressure measurements was poor. From these results, the meaning and value of Doppler derived indirect blood pressure measurements
Answers obtained in psittacine birds remains questionable and should be interpreted as a trend but without relying on the absolute value. Indirect blood pressure (Doppler) measurements were closer to mean arterial pressure measurements than to systolic arterial pressure measurements. Further reading Edling TM, Degernes LA, Flammer K et al. (2001) Capnographic monitoring of anesthetized African grey parrots receiving intermittent positive pressure ventilation. J Am Vet Med Assoc 219(12):1714–1718. Johnston MS, Daviddowski LA, Rao S et al. (2011) Precision of repeated, Doppler-derived indirect blood pressure measurements in conscious psittacine birds. J Avian Med Surg 25(2):83–90. Paré M, Ludders JW, Erb HN (2013) Association of partial pressure of carbon dioxide in expired gas and arterial blood at three different ventilation states in apneic chickens (Gallus domesticus) during air sac insufflation anesthesia. Vet Anaesth Analg 40(3): 245–256. Schmitt PM, Göbel T, Trautvetter E (1998) Evaluation of pulse oximetry as a monitoring method in avian anesthesia. J Avian Med Surg 12(2):91–99. Zehnder AM, Hawkins MG, Pascoe PJ et al. (2009) Evaluation of indirect blood pressure monitoring in awake and anesthetized red-tailed hawks (Buteo jamaicensis): effects of cuff size, cuff placement, and monitoring equipment. Vet Anaesth Anal 36(5):464–479.
CASE 98 1 What are common options for creating an ESF construct or external connecting bar for birds? The common options for creating an ESF construct or external connecting bar for birds are: • Positive profile threaded ESF half-pins connected with an acrylic bar using: ◦◦ Commercial methacrylate based composite (e.g. Acrylx® IMEX). ◦◦ Horse hoof acrylic using a Penrose drain or straw as a mold. • Positive profile threaded half-pins with a FESSA tubular fixator (shown in 98). • Positive profile threaded ESF half-pins connected with a traditional bar and clamp system. 2 What advantages and disadvantages should be considered for each of these constructs? Fixator constructs based on ESF models vary in weight, cost, flexibility, and ease of use. General considerations are that any system used must by extremely versatile, lightweight, removable, effective, and well tolerated. The system with an acrylic bar can be inexpensive, can be countered (curved) as needed, being extremely versatile, and can be made to the exact length. Main drawbacks are the excessive odor during acrylic curing time, and that once it is set, it cannot be adjusted. The FESSA tubular fixator can be used as a guide during transvers pin placement and is more easily adjusted postoperatively than others. It allows easy addition or removal of pins for extra stabilization or dynamic destabilization, as
well as advancing or pulling back transverse pins if needed. The connecting bar is rigid and has fixed length (3, 4.5, 6, 10, 15, 20 cm). The size of the half-pins that can be used with the different sized bars is also limited. The cost of this construct is significantly higher, but it can be re-used. The traditional bar and clamp system is adjustable, requires exact pin placement, and is quite heavy relative to other systems. It is often used as a temporary fixation to stabilize the fracture site prior to surgery to complete an ESF-IM tie-in. 3 What are the advantages and disadvantages of plate fixation in birds compared with these constructs? In birds, an advantage of bone plates is excellent patient tolerance, because plates are completely internal and provide rigid fixation with less callus formation. This might be particularly useful in some species, such as large psittacines and aquatic birds. Disadvantages of bone plating are high costs for instrumentation and implants, specialized training in placing the plates, prolonged anesthesia times, soft tissue disruption, lack of soft tissue in many areas to cover the plate, and potential thermal conduction. One complication associated with bone plating in birds is plate bending. It has been suggested that long bone fractures in birds need to be repaired with longer plates than similar canine and feline fractures. A combination of an IM pin and a bone plate reduces internal plate stress and thereby increases fatigue life of the plate. In general, plates are not removed unless they cause a problem. This should be a consideration in wild birds as ideally all fixation is removed prior to release back to the wild.
CASE 99 1 What are the abnormal radiographic findings? There is an approximately 1.2 cm × 0.7 cm irregular, ovoid, mildy heterogeneous mineral opacity in the mid-caudal coelomic cavity between the ends of the pubic bones. 2 What is the most likely diagnosis? How would you confirm your diagnosis? Acloacolith. Cloacoliths in birds are composed of urates. Uric acid, the main end product of nitrogen catabolism, is excreted with urine by the renal tubules, forming a colloid suspension stabilized by mucopolysaccharides and glycoproteins. These form microspheres that prevent precipitation of urates within the ureters, cloaca, and lower gastrointestinal tract. In supersaturated urine, changes in the solubility and chemistry of the uric acid mucopolysaccharide microspheres may predispose to cloacoliths. Shifts in bacterial flora composition in the distal rectal and coprodeal environment or an improper diet could be considered contributors. Dehydration and infection are likely the most common causes. Nutritional deficiencies might also alter the composition of the protein part of the urine microspheres. A cloacal examination under deep sedation or a cloacoscopy procedure under general anesthesia would confirm the diagnosis.
Answers 3 How would you treat this condition? The cloacolith is gently broken down inside the cloaca with or without the aid of an endoscope. The fragments are then removed and the cloaca is lavaged with warm saline. Systemic antibiotics, since the cloacal mucosa is likely to suffer damage, and analgesia with opioids and local anesthetics are essential. Further reading Beaufrère H, Nevarez J, Tully TN Jr (2010) Cloacolith in a blue-fronted Amazon parrot (Amazona aestiva). J Avian Med Surg 24(2):142–145.
CASE 100 1 What species are these chicks? These neonatal chicks are umbrella cockatoos (Cacatua alba). 2 Are they precocial or altricial? They are altricial, hatched with eyes closed, down is minimal to absent, and mobility is limited. Nourishment, warmth (93–98°F [33.9–36.7°C]), and a safe place must be provided for altricial chicks. 3 What is wrong with the beak of the chick that is sitting up? This chick has a prognathic beak malformation (100b). Cockatoos are prone to prognathism or pug beak. The cause of this beak 100b malformation is unclear but genetics, nutrition, and incubation are suspect. This maxilla beak malformation is characterized by a shorter maxilla (upper beak) that grows into the normal sized mandible (lower beak). If detected, early firm bilateral physical therapy helps to uncurl and pull the upper beak out and over the lower beak. If done several times daily during postnatal development, before beak calcification, it is correctable. If presented later, a rhinotheca extension is attached, so that each time the beak is closed, the rhinotheca is pulled forward. The prosthesis often does not stay on for more than 10 days, but by then the beak will have corrected, so long as this is done while the beak is still soft and not fully developed. Further reading
Romagnano A (2012) Psittacine pediatrics. Vet Clin North Am Exot Anim Pract 15(2): 163–182.
CASE 101 1 The presence of megathrombocytes (enlarged thrombocytes) in avian blood films has been associated with which pathologic process? Chronic inflammatory process. This is commonly observed in species kept in confinement with the tendency to crash repeatedly on the walls or ceiling of the enclosure or cage. A common clinical finding is chronic inflammation of the carpal joint after repeated injuries sustained in captivity. 2 Thrombocyte counts in avian hematology samples are commonly achieved using which quantitative method? Counting directly from the blood film during the differential cell count. 3 What are the main differential morphologic characteristics of thrombocytes in birds? Rectangular shaped cell with basophilic cytoplasm with numerous vacuoles and a rectangular shaped nucleus. Further reading Samour J (2016) Hematology analysis. In: Avian Medicine. (ed. J Samour) Elsevier, St. Louis, pp. 35–52.
CASE 102 1 What are the four key bones involved in elevating and lowering the upper bill? Quadrate, jugal, pterygoid, and palatine. 2 Explain the role of each of these 102b E bones in the kinesis of the psittacine beak. Rotation of the quadrate bones (A) rostrally pushes on the jugals (B) and pterygoids (C), moving them rostrally and resulting in an upward B push being applied to the palatine C bone (D), causing it to slide rostrally on the central boney ridge of the A ventral brain case (os mesethmoidale) (E) and forcing the upper jaw to swing D upward at the craniofacial hinge (protraction) (102b). Rotation of the quadrate bones caudally causes the upper jaw to swing downwards (retraction). 3 How many synovial joints are involved in prokinetic motion of the upper bill, and what bones are they associated with? Fifteen. • Jugal: two bones, synovial joints at both ends (4). • Pterygoid: two bones, synovial joints at both ends (4).
Answers • Palatine: one fused pair, rostral points of articulation (2). • Quadrate: two bones, dual articulation at braincase (neurocranium) (4), jugal, pterygoid (already counted). • Craniofacial hinge (nasofrontal hinge) (ginglymus) (1). (The articulation of the palatine and the os mesethmoidale is a syndesmoidal joint and is not synovial.) Further reading King AS, McLelland J (1984) Skeletomuscular system. In: Birds: Their Structure and Function, 2nd edn. (eds. AS King, J McLelland) Baillière-Tindall, Philadelphia, pp. 43–51.
CASE 103 1 Which two important behavioral events take place in the life of a juvenile parrot (i.e. in the period from hatching to weaning)? (1) (Sexual) imprinting, which is the process by which animals learn the characteristics of appropriate mates by learning the characteristics of their parents or siblings; and (2) socialization, which is the process by which the bird adopts the behavior patterns appropriate to the social environment in which it lives, allowing it to co-exist and interact with other individuals. 2 Provide at least three examples of medical issues that may arise following hand-rearing of psittacine chicks. (1) Reduced growth rate; (2) beak trauma and/ or deformities (e.g. scissors beak, prognathism); (3) crop stasis, overstretching, impaction, and/or trauma (including crop burn and esophageal perforation), with potential secondary infections; (4) aspiration of food, resulting in pneumonia or asphyxiation; (5) hepatic lipidosis (resulting from feeding excessive amounts of high-energy diets); (6) intoxications, particularly of vitamin D (which can result in renal failure and gout); (7) nutritional deficiencies (e.g. hypocalcemia and hypovitaminosis D), which result in metabolic bone disease and bone and joint abnormalities. 3 Provide at least three examples of behavioral problems that may arise following hand-rearing. (1) Delayed weaning and continued begging and whining for food; (2) inappropriate reproductive behavior (e.g. impaired copulatory behavior, floor laying of eggs) resulting in decreased chances of successful reproduction; (3) disrupted social bonds with conspecifics; (4) overbonding to humans; (5)display of inappropriate sexual behavior towards humans (e.g. regurgitation, courtship behavior); (6) (territorial) aggression; (7) fears and phobias; (8) excessive vocalizations; (9) feather damaging behavior and other stereotypies.
Further reading Flammer K, Clubb SL (1994) Neonatology. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Inc., Lake Worth, pp. 805–838. Fox R (2006) Hand-rearing: behavioral impacts and implications for captive parrot welfare. In: Manual of Parrot Behavior. (ed. A Luescher) Blackwell Publishing, Ames, pp. 83–92.
CASE 104 1 What type of organism is infesting these canaries? The organism seen is a feather louse. Based on the broad-based head, this is likely a chewing louse and not a sucking louse. 2 What is the clinical significance of this finding? Lice infestation can lead to irritation, excessive preening, and feather abnormalities in affected canaries. In addition, lice may act as intermediate hosts for parasites such as microfilarids and act as mechanical vectors for avipox virus. 3 What treatment options are available for this flock of 60 birds? Given the large number of individuals in this flock, treatment options that require individual dosing are less than ideal, but include dusting with either a permethrin or carboryl powder product or with fipronil spray (spray on hands and then rub onto feathers). Treatment of the flock may be done by using an aqueous-based ivermectin product in the water. It is important for the client to understand that because the birds live outdoors, they will continuously come into contact with wild birds who can transmit this parasite to his flock. Further reading Macwhirter P (1994) Passeriformes. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, pp. 1172–1199.
CASE 105 1 What is the most likely diagnosis for this mass? Oropharyngeal angiofibroma. Angiofibromas are rare, benign tumors comprised of aggregates of abnormal blood vessels surrounded by connective tissue stroma. This presentation has been described in cockatiels involving the oropharyngeal cavity. 2 How would you confirm your diagnosis? Diagnosis of angiofibromas in man and dogs relies on histopathology and advanced imaging. For resectable cases, such as this one, complete surgical removal remains the treatment of choice. In this case, surgical removal of the angiofibroma was easily achieved by ligation of the ‘stalk-like’ base with two ligatures with 5-0 PDS without hemorrhage. If clear margins are not achieved, follow-up radiation treatment or intralesional chemotherapy should be considered.
Answers 3 What is the prognosis? There is limited information on long-term follow up of excised angiofibromas in birds. In this case and another case published, there was no recurrence a few months after surgery. Recurrence rates in the human literature are variable, with some reports as high as 22.6%. Further reading Doss GA, Miller JA, Steinberg H et al. (2015) Angiofibroma in a cockatiel (Nymphicus hollandicus). J Comp Pathol 152(2–3):274–277.
CASE 106 1 What diagnostic test can be performed antemortem to confirm the diagnosis? Oropharyngeal and cloacal swab samples are used routinely for antemortem diagnosis of WNV infection by detection of infectious particles or viral RNA. Serum samples tested by real time-PCR for WNV could result in a false-negative result despite the high sensitivity of this test due to clearance of the virus from the blood. Different avian species have been shown to be viremic for differing periods of time and with different levels of viremia, with peak viremia occurring approximately 2–4 days post inoculation in most species followed by a decrease or clearance of the virus from the blood. Serology is most useful when applied to paired (acute and convalescent) samples. Plaque reduction neutralization test is the gold standard for anti-WNV antibody detection and titer determination, although cross-reactivity to other flaviviruses (e.g. St. Louis encephalitis virus) is possible. Other antibody tests, such as blocking ELISAs, have been used for highthroughput screening. Virus isolation in Vero cell plaque assay is the gold standard for the confirmation of acute WNV infection. 2 What is the prognosis? What lesions would you expect on postmortem examination? The prognosis for recovery, with severe clinical signs like seizures, is guarded to poor. On gross postmortem examination, no significant lesions except for mild to moderate enlargement of liver and spleen are likely. On histopathology, lymphoplasmacytic and histiocytic hepatitis, interstitial nephritis, myocarditis, splenitis, enteritis, pancreatitis, and encephalitis might be seen. For postmortem diagnosis, virus isolation or RT-PCR testing of homogenized tissue (e.g. kidney, spleen, heart, and brain) might be useful. Detection in tissues is rare more than 2–3weeks after the infection. 3 What treatment and preventive measures would you recommend? Treatment of WNV infection in birds consists of supportive care, such as fluid electrolyte therapy, supplemental heat or cold, antibiotic or antifungal agents to treat or prevent secondary infections, assisted feeding or nutritional supplementation, NSAIDs, and anticonvulsants if needed. Because there is no specific treatment for WNV infection in birds, minimizing mosquito contact to lessen the likelihood of
infection is crucial. Smaller scale strategies include eliminating standing water, covering upright containers, and filling holes or depressions. For captive birds housed outdoors, mosquito nets or screens may be used to cover caging. Alternately, bird-safe mosquito repellents (e.g. geraniol, Fasst Products) aerosolized around caging have been shown to deter mosquitoes. Although no WNV vaccinations are currently approved for use in birds, several commercially available equine vaccines (e.g. killed and recombinant canarypox-vectored vaccines) have been tested in birds. Seroconversion rates are generally low following vaccination and may vary by species and vaccine construction. Few data are available regarding vaccineinduced protection against virus challenge. Further reading Stockman J, Hawkins MG, Burns RE et al. (2010) West Nile virus infection in a greenwinged macaw (Ara chloropterus). Avian Dis 54(1):164–169.
CASE 107 1 What are the effects of oiling on individual birds? Individual birds may be directly contaminated by external oiling, ingestion of oil, respiration of volatile components, or by contamination of embryos through the egg shell. External contamination is the most important, resulting in high mortality due to the bird’s inability to repel water, thermoregulate, and fly. Ingestion may lead to disruption in nutrient absorption and subsequent diarrhea, anorexia, regurgitation, and hemorrhage. Polycyclic aromatic hydrocarbons can damage directly the respiratory system and result in systemic toxicity. Oxidative damage to red blood cells may lead to hemolytic anemia. Immunosuppression and reproductive impairment are also known direct effects. 2 What are the different steps in the process of caring for oiled birds? Recovery of oiled birds from the environment and transport to a rehabilitation center or field stabilization site, processing and intake, stabilization, cleaning, pre-release conditioning, and release back to the wild. The washing and rinsing procedures are the most stressful steps in the rehabilitation process. Birds that have not been stabilized prior to washing often die. The stabilization process usually requires 48hours of indoor care before washing. The bird should meet minimum health criteria (e.g.adequate packed cell volume, total plasma protein concentration, blood glucose concentration, and absence of infectious disease) before being washed. The exception to stabilization before washing is in cases of highly volatile products. The birds are washed initially to remove the bulk of the toxic material quickly, but not to restore waterproofing. A second bath and rinse procedure is required after stabilization. 3 How would you prevent secondary diseases in this process? Prophylactic antifungals and 10–15 air changes per hour to prevent respiratory aspergillosis. Net-bottomed cages to prevent pododermatitis and keel ‘donuts’ over the keel to prevent pressure sores are some of the common considerations for these problems.
Answers Further reading Mazet JAK, Newman S, Gilardi KVK et al. (2002) Advances in oiled bird emergency medicine and management. J Avian Med Surg 16(2):146–149.
CASE 108 1 What is the most likely diagnosis? Renal neoplasia (e.g. adenocarcinoma, adenoma). Renal masses occur more frequently in young to middle-aged male budgerigars and are often located in the anterior division of the affected kidney. This clinical sign results from tumor compression of the ischiadic nerve as it passes through the kidney or from tumor growth adjacent to the synsacrum and ilium. Although these tumors rarely metastasize, local infiltration of the spine, as seen in this case, has been reported. Some cases may also have other clinical signs such as lethargy, loss of body condition, coelomic distension, dyspnea due to the intracoelomic pressure or organ displacement. 2 What diagnostic test would you perform to confirm your diagnosis? CBC, plasma biochemistry panel, survey and contrast gastrointestinal radiographs, and ultrasound of the coelomic cavity. In the cases reported, uric acid does not seem to be a sensitive indicator of renal neoplasia unless affecting both kidneys. On plain radiographs, the position of the grit-filled ventriculus relative to the kidneys can be used as a landmark for changes in renal size. Also, normal sized kidneys do not extend ventral to an imaginary horizontal line parallel to the spine that passes through the ventral border of the acetabulum. In contrast radiographs, lateral displacement of the proventriculus and caudal displacement of the ventriculus on the VD view, and ventral displacement of the intestines and ventriculus in the laterolateral view might be present depending on the size and location of the mass. High-frequency transducers with a small contact surface are necessary to obtain diagnostic ultrasonographic images in these cases. 3 What are the treatment options and prognosis? Therapeutic options for renal neoplasia in budgerigars are limited due to the bird’s small size and the location of the tumor. There are no reports of successful surgical treatment. The short distance of their artery to the aorta makes ligation and hemostasis difficult or impossible with the current techniques. There are anecdotal reports of chemotherapy treatment. The platinum analog carboplatin (5 mg/kg diluted 1:10 with sterile water IV once a month for 3 months) has been reported in one case, which seemed to alleviate signs for a few weeks. Analgesics (e.g. tramadol) and NSAIDs (e.g. meloxicam) have been used anecdotally to alleviate pain associated with the growing mass. More information is needed on chemotherapeutic agents in budgerigars before further recommendations are made.
Further reading Simova-Curd S, Nitzl D, Mayer J et al. (2006) Clinical approach to renal neoplasia in budgerigars (Melopsittacus undulatus). J Small Anim Pract 47:504–511.
CASE 109 1 What is the most likely cause of the lesions noted around the joints? Articular gout is caused by deposition of uric acid crystals in the synovial capsules and tendon sheaths of joints. This is secondary to hyperuricemia likely related to renal disease and inability to clear the uric acid from circulation. To confirm the diagnosis, a fine needle aspirate and cytology (do not fix with alcohol as it will dissolve the uric acid crystals) or a murexide test should be performed. To perform a murexide test: a drop of nitric acid is mixed with a small amount of suspected material on a slide and dried by evaporation in a Bunsen flame. After cooling, one drop of concentrated ammonia is added. In the presence of urates, a mauve (pale purple) color will develop. Alternatively, a polarizing microscope can be used to identify urate crystals. 2 What medications can be used to help this patient? Analgesics (e.g. opioids or opioid-like) can be used to provide palliative relief since these lesions are typically painful. Surgery to remove the uric acid crystal deposits will not be feasible in most cases. To slow progression of the disease, allopurinol can be administered orally. This medication is a competitive xanthine oxidase inhibitor that blocks the conversion of xanthine into uric acid. As allopurinol is contraindicated in some birds of prey, urate oxidase may be used in these species as well as pigeons. Urate oxidase catalyzes the conversion of urate and oxygen into allantoin and hydrogen peroxide. Additionally, colchicine reversibly inhibits xanthine dehydrogenase and has been used anecdotally in some avian species. None of these medications will decrease the crystals that are already present in the joints. Probencid, a uricosuric drug used in people that acts mostly by reducing the absorption of uric acid in the tubuli, appears to be contraindicated in birds. Birds lack the reabsorptive mechanism of uric acid and probencid could further reduce the active secretion of uric acid into the tubuli. A low protein diet could potentially slow down the progression of the disease, although this has not been clinically evaluated in birds. 3 What other systems may be affected by this disease? Visceral gout can also occur. This occurs when excessive plasma uric acid levels are present and these crystals precipitate on various organs such as the liver, spleen, and pericardium, as well as in the kidneys. Further reading Burgos-Rodríguez, Armando G (2010) Avian renal system: clinical implications. Vet Clin North Am Exot Anim Pract 13(3):393–411.
Answers Fudge AM (2000) Laboratory reference ranges for selected avian, mammalian, and reptilian species. In: Laboratory Medicine Avian and Exotic Pets. (ed. AM Fudge) WB Saunders, Philadelphia, pp. 375–400. Poffers J, Lumeij JT, Redig PT (2002) Investigations into the uricolytic properties of urate oxidase in a granivorous (Columba livia domestica) and in a carnivorous (Buteo jamaicensis) avian species. Avian Pathol 31(2):573–579.
CASE 110 1 What are the differential diagnoses for ‘swollen head syndrome’ in pheasants and/or partridges (110)? The so called ‘swollen head syndrome’ can be caused by one type of virus or bacteria or, most commonly, by a mixed viral and bacterial infection. The top four possible differentials would be: Mycoplasma gallisepticum (Mg), avian rhinotracheitis (ART) caused by pneumovirus, infectious bronchitis (IB) caused by coronavirus, and various secondary bacteria such as E. coli, Pasturella spp., and Ornithobacterium rhinotracheale (ORT). 2 What are the most appropriate tests available to diagnose the cause of this syndrome? Although in theory serologic testing would give an indication as to exposure, it does not help identify the current causative organisms. The best diagnostic procedures would be to take multiple swabs of the trachea/sinuses and cloaca for PCR techniques. These swabs can be sent off to a laboratory to identify if ART/Mg/IB or ORT are present. Swab samples should also be taken of the trachea and sinuses and placed in a charcoal-based medium for laboratory culturing and antibiotic sensitivity testing; this type of swab will identify the most likely secondary bacterial infections such as E. coli or Pasturella spp. 3 What are the most appropriate treatment methods available for flocks of pheasants and partridges? This syndrome can often be difficult to treat and resolve due to the nature of the disease involved, as both ART and IB, if found, are caused by viruses and there is no current treatment available. Mycoplasma is a bacterium that will likely infect the bird for life and although antibiotics will reduce the clinical signs, they will often return when the bird becomes stressed again. Inthe UK, AivlosinTM (tylvalosin) is the only licensed antibiotic for Mycoplasma in pheasants. This product is administered in the drinking water for 3 days. If other bacteria are identified, then the use of an off-license product may be applicable, but since withdrawal periods are unknown in these cases, the choices for animals that might enter the food chain are limited. Further reading Bradbury JM, Yavari CA, Dare CM (2001) Mycoplasmas and respiratory disease in pheasants and partridges. Avian Pathol 30:4:391–396.
CASE 111 1 Describe the anatomic entry points for a double-entry orchidectomy. The first entry point is made caudal to the last rib, cranial to the pubis bone, and ventral to flexor cruris medialis muscle, identical 111b to that used for single-entry diagnostic m coelioscopy (111b, black arrow). Following insertion of a telescope, a second port is created under endoscopic guidance, caudal to the pubic bone (11b, white arrow) and ventral to the flexor cruris medialis muscle (111b, m). 2 Name the structures labeled (2), (3), and (4) in image 111a that are closely associated with the left avian testis (1) and need to be avoided during orchidectomy. Avian testes are located very close to the left adrenal gland (4), the cranial division of the left kidney (2), and the common iliac vein converging into the caudal vena cava (3), and are suspended by a short mesorchium. This makes inadvertent entrapment of or coagulative damage to these structures, including severe hemorrhage, important considerations during orchidectomy. 3 What are the possible complications of a single-entry vasectomy technique in birds? Ureter perforation and hemorrhage are the most commonly reported complications of an endoscopic vasectomy. Further reading Heiderich E, Schildger B, Lierz M (2015) Endoscopic vasectomy of male feral pigeons (Columba livia) as a possible method of population control. J Avian Med Surg 29(1): 9–17. Hernandez-Divers SJ, Stahl S, Wilson GH et al. (2007) Endoscopic orchidectomy and salpingohysterectomy of pigeons (Columba livia): an avian model for minimally invasive endosurgery. J Avian Med Surg 21(1):22–37.
CASE 112 1 What is the most likely date of death? From the maggot size, the estimate is December 3rd. 2 What do you believe the bird’s normal flying weight would be? The bird’s P8 length (368.5 mm) is three SDs (3 × 11.5) less than the average of 403 mm. This means that the bird is very small for its species and so one would expect its ‘fat weight’ to be three SDs (3 × 123.6 g) less than the species average weight (1,105 g) (i.e. 734.2 g).
Answers As the bird was in the middle of a flying season (hence at flying weight), he would ordinarily be expected to be some way below ‘fat weight’. The flying weight of a nonimprint falcon would normally be 5–10% less than its fat weight (i.e. 36– 72 g less than this bird’s fat weight). In this bird its flying weight would therefore be expected to be 734.2 g less 36–72 g = 662–698 g. 3 How long do you think it could have been starved for? The postmortem weight was 645 g. The bird had not been fed the previous evening (as the gastrointestinal tract was empty). It was also dehydrated and had had no water available. This was winter time (i.e. cold) and an unfed bird would lose weight fast. Considering the bird’s likely flying weight, its postmortem weight, and the findings of diarrhea and dehydration, one would not have expected this bird to have been ill for more than 1–2 days prior to death (i.e. not prior to November 30th). The client was hospitalized before the bird became ill. Further reading
Amendt J, Krettek R, Zehner R (2004) Forensic entomology. Naturwissenschaften 91:51–65.
CASE 113 1 What abnormality is seen to be affecting which eye in this sparrow hawk? Right eye hyphema and uveitis. 2 What is the most common cause for this disorder in birds? Blunt or sharp trauma in birds can cause anterior and/or posterior uveitis, frequently associated with hyphema. Other differential diagnoses for uveitis in birds include infections, immune-mediated inflammation, and neoplasia. Clotting disorders tend to manifest bilaterally and systemically. 3 What ophthalmologic tests should be conducted? After completing a full physical examination including assessment of the periocular structures, additional ophthalmologic diagnostic tests can be used to evaluate the consequences of trauma within the eye. Anatomic particularities of the raptor eye mean they respond differently to blunt trauma compared with mammals. The shape of the eye is normally maintained by the scleral ossicles even in cases of severe blunt trauma. If asymmetries are suspected, radiographs, CT or MRI may be of value in diagnosing periocular and intraocular disorders. The avian cornea is larger and less protected by periocular bones compared with those of mammals, which, in combination with the longitudinal shape of the globe in some species, means that blunt trauma typically results in lesions of greater severity within the posterior rather than the anterior segment. Direct and indirect ophthalmoscopy and slit lamp microscopy permit examination of the anterior and posterior chambers and should be used in all avian trauma cases, even when there is no external indication of ocular damage. Tonometry measures the intraocular pressure. Fluorescein dye
test allows assessment of the integrity of the cornea. Ocular ultrasonography may aid in the diagnosis of some disorders in the posterior segment of the eye, whereas electroretinography is useful to assess the retinal function. Further reading Seruca C, Molina-López R, Peña T et al. (2012) Ocular consequences of blunt trauma in two species of nocturnal raptors (Athene noctua and Otus scops). Vet Ophthalmol 15(4):236–244.
CASE 114 1 What is your top differential diagnosis for the cause of death in these ducklings? Based on the clinical history of this disease within the flock, it is highly suspicious that these ducklings died as the result of duck hepatitis virus (DHV) type 1. DHV1 is an Avihepatovirus in the family Picornaviridae, is internationally widespread, and is highly virulent in young ducklings. 2 What pathologic changes do you expect to see on gross necropsy? Typical lesions associated with DHV-1 include hepatomegaly with hemorrhagic foci, splenomegaly, and swelling of the kidneys with congestion of the renal vasculature. 3 In addition to necropsy, what diagnostic tests should be performed to confirm the cause of this die-off? Virus isolation from the liver tissue of affected ducklings is the most common confirmatory test performed for DHV-1. Virus neutralization and PCR testing are also available but less widely used. Further reading Woolcock PR (2015) Duck viral hepatitis. OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. Accessed online at: http://www.oie.int/international-standardsetting/terrestrial-manual/access-online/
CASE 115 1 What gross lesions are shown in the image? The presence of white material throughout the serosa of visceral organs and within the kidneys is characteristic of visceral gout (115b). 2 What is the histologic lesion? The tophi are deposits of uric acid in the parenchyma of the organ. Tissues should be harvested into alcohol (not formalin), as urates dissolve in the latter. Histopathology of the affected organ will confirm the presence of uric acid crystals in the organs. 3 What is the pathophysiology of this disease? Uric acid is the primary nonnitrogenous waste product of avian kidneys. When avian kidneys are in endstage renal disease, they are unable to actively secrete uric acid. The resulting
Answers hyperuricemia causes precipitation of this nonsoluble product on the serosal surface of many visceral organs; this tends to be an acute/peracute end-stage presentation. Articular gout (precipitation of uric acid in joint spaces) can also develop following chronic kidney disease (CKD), and the combination of visceral and articular gout is often observed in birds with CKD; however, this swan only had visceral gout, and all ofthe examined joints were grossly normal. The underlying cause for renal disease in this swan was never determined. In other waterfowl, lead toxicosis, nutritional (i.e. excess dietary protein, hypovitaminosis A), and other toxin exposure (oil exposure, mycotoxins) have been associated with development of CKD.
Further reading Speer BL (1997) Urogenital disorders. In: Avian Medicine and Surgery. (eds. R Altman, S Clubb, G Dorrestein, K Quesenberry) WB Saunders, Philadelphia, pp. 625–644.
CASE 116 1 What surgical procedure would you perform to resolve this condition? Salpingohysterectomy, as the oviduct and not the ovary is removed. Ovariectomies in birds are technically difficult and carry a high risk of hemorrhage or incomplete resection. 2 How would you perform this procedure? The bird is positioned in right lateral recumbency and the left leg may be retracted cranially to increase exposure of the cranial and caudal coelom, respectively. The skin is incised over the left paralumbar region from the last rib to the caudal aspect of the pubic bone. The abdominal muscles are incised and the superficial medial femoral artery and vein over the lumbar fossa should be cauterized. The last two ribs might be transected to provide adequate exposure of the cranial coelomic cavity. The ventral ligament is dissected to allow the oviduct to be released and positioned in a linear fashion. The fimbria of the infundibulum lies caudal to the ovary and may be elevated to expose the dorsal ligament. A small blood vessel can be identified coursing from the ovary through the infundibulum and should be coagulated and dissected. The remainder of the dorsal suspensory ligament may then be dissected, from craniad to caudal,
with hemostasis of the vasculature with radiosurgery or hemoclips. The oviduct is retracted ventrally and caudally as it is released. It is ligated at its junction with the vagina a short distance from the cloaca. Closure is in 2–3 layers and is routine with 3-0 to 5-0 monofilament absorbable suture. 3 What intra- and postoperative complications might occur? Intraoperative complications include hemorrhage if there is inadequate hemostasis during dissection of the dorsal ligament of the oviduct, and damage to the ureters during caudal dissection of the oviduct before entering the cloaca. If the oviduct is friable, contamination of the field is likely without careful manipulation of the tissue. Postoperative complications include peritonitis, airsacculitis, and pneumonia if there was contamination of the peritoneum or air sacs during the procedure, and internal ovulation and egg yolk peritonitis if the bird continues ovulating in the future. Administration of GnRH agonists (e.g. deslorelin acetate implants) is recommended to avoid the latter. Further reading
Guzman DS (2016) Avian soft tissue surgery. Vet Clin North Am Exot Anim Pract 19(1): 133–157.
CASE 117 1 What major structure will be revealed if the kidneys of this yellow-crowned Amazon parrot (Amazona ochrecephala) are dissected away? The kidneys lie in the renal fossa formed by the pelvis, which 117b is fused to the synsacrum. Between the fossa and the kidney is the lumbosacral plexus forming the femoral nerve (F), obturator nerve (O) and the ilioischiadic nerve (I) (117b: 1 = cranial division; 2 = intermediate division; 3 = caudal 1 F division; 4 = lumbosacral plexus). 2 How can disease in this area cause O 4 paralysis of the legs? Because of the I close proximity of the nerves to the kidneys, nephritis can frequently cause 2 neuritis; likewise, renal neoplasia will cause pressure on the nerves. In both 3 cases the legs can become paralyzed.
Answers CASE 118 1 What is the correct terminology for the behavior modification techniques that can be used to decrease the conditioned fear response? Also explain briefly how these techniques work. The most commonly used technique to reduce fear and phobias is systematic desensitization, which involves the gradual and systematic exposure to a stimulus until the conditioned response to the stimulus is extinguished. To boost its effects, the procedure is combined with counterconditioning, during which a positive stimulus is noncontingently paired with the aversive stimulus to change the value of the conditioned stimulus. Flooding (also referred to as response blocking) is another technique that can be used, but due to its negative side-effects (e.g. promotion of learned helplessness due to depriving the animal of the ability to choose) veterinarians are discouraged from using this technique. 2 What are the key factors that need to be taken into consideration for the successful implementation of the above mentioned procedure? Key to a successful implementation of systematic desensitization are the following: the owner needs to be able to recognize what calm behavior looks like in their parrot by assessing the parrot’s activities as well as its plumage, eyes, and the position of its head, body, and legs; the fear-eliciting stimulus can be identified, reproduced, and controlled (in terms of distance, intensity, or duration, but also in terms of its occurrence outside of the behavior modification sessions); the stimulus is initially presented at a low enough duration, intensity, or far enough distance to prevent eliciting a fear response; the incremental steps are sufficiently small to prevent the triggering of a fearful response; and advancement of the next step only occurs if the animal remains calm in the presence of the stimulus at that level. 3 In case of extreme fear or patients being refractory to behavior modification therapy, pharmacologic intervention may be considered. What drug classes may be used to reduce anxiety? Pharmacologic treatment options for fear or phobias include: benzodiazepines (e.g. diazepam, midazolam, lorazepam); tricyclic antidepressants (e.g. amitriptyline, doxepin, clomipramine); (selective) serotonin reuptake inhibitors (e.g. fluoxetine, paroxetine); and azapirone derivatives (e.g. buspirone). Further reading Martin KM (2006) Psittacine behavioral pharmacotherapy. In: Manual of Parrot Behavior. (ed. A Luescher) Blackwell Publishing, Ames, pp. 267–279. van Zeeland YRA, Friedman SG, Bergman L (2016) Behavior. In: Current Therapy in Avian Medicine and Surgery. (ed. BL Speer) Elsevier, St. Louis, pp. 177–251. Wilson L, Luescher AU (2006) Parrots and fear. In: Manual of Parrot Behavior. (ed. ALuescher) Blackwell Publishing, Ames, pp. 225–231.
CASE 119 1 Which crop shape corresponds to the following bird species: budgerigar, cormorant, pigeon, chicken, vulture? (a) Cormorant; (b) vulture; (c) chicken; (d)pigeon; (e) budgerigar. The simplest form is merely a spindle-shaped enlargement of the cervical esophagus, which is also present in ducks, geese, and a number of songbirds. Parrots have well-developed crops that lie at the caudal cervical esophagus. A prominent right pouch and a small left pouch typify parrots. Pigeon crops have a more complicated structure. Both right and left lateral pouches or diverticulae are well developed. 2 Which bird species lack a true crop? A common misconception is that all birds have a crop, but it is absent in many groups including owls, toucans, gulls, and penguins. 3 Which bird species are known to produce secretions in the crop or esophagus that are used to feed the chicks? Pigeons secrete nutrients into the crop. In pigeons the epithelium of the crop thickens by the 13th day of egg incubation. The epithelial cells accumulate protein and fat, which are subsequently shed into the lumen. This holocrine secretion is referred to as crop milk. It contains 12.4% protein, 8.6% lipids, 1.37% ash, and 74% water. It is predominantly a protein and fatty acid source for their chicks, and is devoid of carbohydrate and calcium. Both parents produce crop milk. The pituitary hormone that controls the secretion of nutrients into the crop is prolactin, which is produced in the cephalic lobe of the adenohypophysis. Male emperor penguins (Aptenodytes forsteri) produce a similar holocrine secretion into the esophagus that also consists of desquamated epithelial cells. Greater flamingos (Phoenicopterus roseus) also secrete nutrients into the esophagus. Esophageal mucous glands produce a merocrine secretion that is fed to the young. Further reading Klasing KC (1998) Anatomy and physiology of the digestive system. In: Comparative Avian Nutrition. CAB International, Wallingford, pp. 20–21. Lumeij JT (1994) Gastroenterology and endocrinology. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Inc., Lake Worth, pp. 490 and 584.
CASE 120 1 Based on the history and physical examination findings, what are your differential diagnoses? Lead toxicosis, West Nile virus infection, avian influenza infection, inanition due to extreme weather condition, trauma, advanced aspergillosis. 2 What diagnostic test would you perform to confirm the diagnosis? Hematology and blood chemistry; blood sample for measuring lead concentrations; blood sample for serology for virology; oropharyngeal and/or cloacal PCR for virology.
Answers 3 The falcon appeared to be suffering from lead toxicosis. How is it possible to have such a high lead level? Which is the ideal therapeutic agent for treatment? Serology for West Nile virus and influenza infection was negative. No lead pellets or particles were observed in the gastrointestinal tract. Lead level was 6.52 µmol/L (135 µg/dL) (reference interval 2 weeks old. An inactivated vaccine, which appears to be as efficacious as the modified live vaccine, has not been tested on a large scale and is not currently licensed. Further reading Banda A (2013) Overview of duck viral enteritis. The Merck Veterinary Manual (last full review/revision August 2013). www.merckvetmanual.com/poultry/duck-viral-enteritis/ overview-of-duck-viral-enteritis Campagnolo ER, Banerjee M, Panigrahy B et al. (2001) An outbreak of duck viral enteritis (duck plague) in domestic Muscovy ducks (Cairina moschata domesticus) in Illinois. Avian Dis 45(2):522–528.
CASE 136 1 What is the most likely etiology of the observed clinical signs? Anticoagulant rodenticide toxicity is a common cause of coagulopathy in birds of prey. Any prey that has ingested a rodenticide bait could potentially be a source of secondary exposure for a hawk, including rodents and invertebrates. Other coagulopathies, for instance from hepatic insufficiency, can be considered. The coelomic distension could be due to a hemocoelom associated with a compression of the air sac, causing increased respiratory efforts. 2 How would you confirm your presumptive diagnosis? The presumptive diagnosis can be confirmed by measuring blood concentrations of a panel of anticoagulant rodenticides including brodifacoum, which has been reported as the most common anticoagulant found in birds of prey in various states of the USA. Alternatively, the same panel can be performed on a liver sample post mortem. Routine blood tests may also show anemia, hypoproteinemia, and prolonged whole blood clotting time. 3 How would you treat this bird? Vitamin K1 is administered at 2.5 mg/kg IM or SC q4–12h, then at 2.5 mg/kg PO q24h when the bird is able to eat. The duration of treatment depends on the generation of anticoagulant rodenticide, with a 3–4-week long treatment recommended for second generation anticoagulants. The hematocrit may be evaluated a few days after discontinuing vitamin K1 administration. Whole blood transfusions may also be administered as needed. Vision should be evaluated to assess releasability in this case. Further reading Murray M (2011) Anticoagulant rodenticide exposure and toxicosis in four species of birds of prey presented to a wildlife clinic in Massachusetts, 2006–2010. J Zoo Wildl Med 42(1):88–97. Murray M, Tseng F (2008) Diagnosis and treatment of secondary anticoagulant rodenticide toxicosis in a red-tailed hawk (Buteo jamaicensis). J Avian Med Surg 22(1):41–46. (Treatment doses in Part 3.) Redig PT, Arent LR (2008) Raptor toxicology. Vet Clin North Am Exot Anim Pract 11(2):261–282. Stansley WI, Cummings M, Vudathala D et al. (2014) Anticoagulant rodenticides in redtailed hawks, Buteo jamaicensis, and great horned owls, Bubo virginianus, from New Jersey, USA, 2008–2010. Bull Environ Contam Toxicol 92(1):6–9. Thomas PJ, Mineau P, Shore RF et al. (2011) Second generation anticoagulant rodenticides in predatory birds: probabilistic characterization of toxic liver concentrations and implications for predatory bird populations in Canada. Environ Int 37:914–920. Wenick (2013) Comparison of fluid types for resuscitation in acute hemorrhagic shock and evaluation of gastric luminal and transcutaneous PCO2 in leghorn chickens. J Avian Med Surg 27(2):109–119. (End of answer Part 3.)
Answers CASE 137 1 What is the function of the foramen 137b formed by the union of the scapula, coracoid, and clavicle? Does it have 1 any clinical significance? The tendon of the supracoracoid muscle runs through 2 3 7 the triosseal canal, which acts as a pulley, allowing the wing to be raised 4 by the ventrally placed muscle found underlying the pectoral muscle (137b; 8 1 = coracoid; 2 = tendon of supracoid muscle; 3 = acrocoracoid ligament; 4 = humerus; 5 = ribs; 6 = supracoracoid 5 muscle entering triosseal canal; 8 = supracoracoid muscle; 9 = cut edge 9 of removed pectoral muscle). The 6 supracoracoid tendon can be ruptured as a result of trauma and the bird is then unable to lift its wing; the tendon must be repaired in order to allow the bird to fly again. Fractures of this region are often seen after a wild bird flies head on into a window. Fractures are sometimes treated by immobilizing the wing, although this will allow callus around the triosseal canal to adhere to the supracoracoid tendon, causing permanent dysfunction of the wing. Multiple fractures in this region may be treated successfully with rest in a restricted area and no immobilization.
CASE 138 1 Briefly explain the theory behind the two imaging modalities. CT is a diagnostic imaging technique that uses x-rays to obtain cross-sectional images of the body, thereby overcoming the issue of superimposition of tissues and structures as seen in conventional radiography. With the help of special software, the obtained images can furthermore be digitally processed to obtain 3D views and/or reconstruct the data into alternate planes. MRI, in contrast, uses a powerful magnetic field in combination with highfrequency radio waves to align and spin protons (hydrogen atoms) in the body and obtain signals resulting from the spinning protons. As most hydrogen atoms are trapped in water molecules, an MR image is mainly a representation of the different types, distributions, and volumes of water in the various tissues. 2 What are the main applications for both imaging modalities in birds? CT imaging is mainly performed to assess known or suspected abnormalities in the skeletal
structures and respiratory tract. In birds, CT has been proven particularly helpful in diagnosing lower respiratory tract disease, but is also considered superior to radiographs for evaluating the nasal cavity, conchae, and sinuses as well as skeletal tissues with significant superimposition of overlying soft tissue structures such as the spine, shoulder joint, pelvis, and skull (in particular the hyoid bone and beak apparatus). Enlargement of various intracoelomic organs, such as liver, kidney, and spleen, may also be detected with CT imaging, especially when contrast medium is used. The gastrointestinal tract can also be visualized, although recognition of pathology is often more difficult without the use of an intraluminal contrast medium such as barium sulfate. The central nervous system, unless the lesions are severe (e.g. severe hydrocephalus), is best evaluated with MRI. CT angiography enables evaluation of the larger vessels, facilitating diagnosis of cardiovascular diseases. MRI is used primarily to diagnose soft tissue changes. In birds, MRI has mainly been used for diagnosing neurologic disease (e.g. brain and spinal cord abnormalities such as hydrocephalus, ischemic strokes, and spinal cord trauma). MRI is also considered an excellent tool for evaluating the eye, orbit, and sinuses and may also have value when evaluating internal organs such as the gastrointestinal tract, liver, spleen, and urogenital tract. In contrast, MRI is less useful for imaging the heart and lungs because of the artifacts created by the cardiac motion, which hinder proper visualization of the heart and lungs. 3 What are the main limitations of both techniques with regard to their use in avian medicine? In practice, limitations of CT are mainly dependent on the spatial resolution of the CT scanner and size of the patient. Particularly in smaller sized birds, the resolution of most CT scanners may be poor, limiting its diagnostic value for evaluating organs and structures. Additionally, factors such as differences in density between the object of interest and its surrounding structures and the size of the object may play a role in the visualization of abnormalities. The use of MRI in avian medicine is limited, predominantly because of the prolonged time needed to perform the MRI scan, resulting in a prolonged anesthesia, which may carry additional risks for the patient, especially since there is limited access to the patient during the procedure. Additionally, the relatively low spatial resolution of some systems (1 kg), which shows that it may be of use in these larger species. 2 What are the main sources of variability in the measurement of indirect blood pressure in parrots using a sphygmomanometer and a Doppler flow unit? What are the clinical implications? A study in psittacines showed that the main sources of variability were cuff placement and individual birds, whereas the limb used was not a significant source of variability. As a result, monitoring trends in indirect blood pressure measurement following a single cuff placement event, such as during anesthetic monitoring, may be useful. 3 Which sites and arteries are used for direct blood pressure measurement in birds? In medium to large sized birds, invasive blood pressure measurements through arterial catheterization may be obtained to improve anesthetic monitoring.
Answers Themost accessible arteries for catheterization are the superficial ulnar artery, the deep radial artery, the external carotid artery (requires a cut-down procedure), and the cranial tibial artery. In smaller birds, significant bleeding may be encountered during catheter removal and fatal bleedings have been experienced in research birds up to 24 hours following arterial catheter removal. Further reading Acierno MJ, da Cunha A, Smith J et al. (2008) Agreement between direct and indirect blood pressure measurements obtained from anesthetized Hispaniolan Amazon parrots. J Am Vet Med Assoc 233(10):1587–1590. Johnston MS, Davidowski LA, Rao S et al. (2011) Precision of repeated, Doppler-derived indirect blood pressure measurements in conscious psittacine birds. J Avian Med Surg 25(2):83–90. Schnellbacher R, da Cunha, Olson EE et al. (2014) Arterial catheterization, interpretation, and treatment of arterial blood pressures and blood gases in birds. J Exot Pet Med 23(2):129–141. Zehnder AM, Hawkins MG, Pascoe PJ et al. (2009) Evaluation of indirect blood pressure monitoring in awake and anesthetized red-tailed hawks (Buteo jamaicensis): effects of cuff size, cuff placement, and monitoring equipment. Vet Anesth Analg 36(5):464–479.
CASE 148 1 Review the image shown and name the structures identified with the black and green arrows. Black arrow = thyroid gland; green arrow = parathyroid gland and ultimobranchial gland. 2 List at least two histologic or physiologic features of these structures that are similar and two that are different from those described in mammals. Similar: (1)thyroid gland formed by follicles lined by a single layer of epithelial cells and filled with colloid (thyroglobulin); (2) the mechanism of synthesis and release of T4 and T3, with T3 production being mostly extrathyroidal; and (3) calcium metabolism is regulated by parathyroid hormone, calcitonin, and 1,25-dihydroxy vitamin D3. Different: (1) calcitonin secreting cells (parafollicular cells in mammals) are not within the avian thyroid gland, but form a separate gland, the ultimobrachial gland, which is located caudal to the parathyroid glands; (2) the avian thyroid gland produces relatively more T4 than T3, although avian plasma contains less T4 and similar concentrations of T3 compared with mammals; (3) avian thyroidstimulating hormone (TSH) has a different structure than mammalian TSH; (4)calcium metabolism adjustments in birds occur faster than in mammals; (5)the number of parathyroid glands in birds varies between two and four depending on the species; (6) the parathyroid gland consists primarily of chief cells – it does not contain the oxyphil cells found in mammalian parathyroid glands; and (7) birds have high circulating levels of calcitonin.
3 Which disease processes have been described relating to these two structures in avian species? Diseases of the thyroid gland include goiter, hyperthyroidism, and hypothyroidism. 4 Which specific assays can be used to investigate the function of these structures in birds? Assays for evaluation of the thyroid gland include measurement of T4 blood levels pre- and post-TSH administration and measurement of free T4. Low blood levels of T4 and response to L-thyroxine supplementation may be suggestive of hypothyroidism, but measuring T4 blood levels pre- and post-TSH administration is required for an accurate diagnosis. Diseases of the parathyroid gland include nutritional secondary hyperparathyroidism and adenoma. Primary hypoparathyroidism or hyperparathyroidism, renal secondary hyperparathyroidism, tertiary hyperparathyroidism and pseudohypoparathyroidism have not been reported in avian species. Assays for evaluation of the parathyroid gland function include evaluation of total calcium and ionized blood calcium levels, determination of blood levels of parathyroid hormone, and determination of blood levels of vitamin D3. Further reading Brandao J, Manickam B, Blas-Machado U et al. (2012) Productive thyroid follicular carcinoma in a wild barred owl (Strix varia). J Vet Diagn Invest 24(6):1145–1150. de Matos R (2008) Calcium metabolism in birds. Vet Clin North Am Exot Anim Pract 11:59–82. Hudelson KS, Hudelson PM (2006) Endocrine considerations. In: Clinical Avian Medicine. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 541–557. King AS, McLelland J (1984) Endocrine system. In: Birds, Their Structure and Function, 2nd edn. Baillière Tindall, Eastbourne, pp. 200–213. McNabb FM, Darras VM (2015) Thyroids. In: Sturkie’s Avian Physiology, 6th edn. (ed. CG Scanes) Academic Press, Waltham, pp. 535–547. Schmidt RE, Reavill DR, Phalen DN (2015) Endocrine system. In: Pathology of Pet and Aviary Birds, 2nd edn. Iowa State Press, Ames, pp. 161–174.
CASE 149 1 What condition is the bird suffering from, and what investigations should be carried out on the other youngsters? This bird is suffering from a ‘crop burn’. Excessively hot food has been fed to the bird; this occurs most commonly when food has been heated in a microwave and not adequately mixed prior to feeding, resulting in hot spots within the bowl of food. It is not uncommon for only one or two chicks fed from the same bowl to be affected. In respect of the other two birds, careful examination of the crop is required. Itis not uncommon for partial-thickness burns to occur, so no leakage is detected. Any chick with delayed emptying should be checked, by way of a crop swab, for abnormal bacterial or fungal (Candida spp.) infection. If a partial-thickness burn is
Answers present, antibiotics and/or antifungals, as indicated by cytology or culture, should be maintained until the lesion has healed and resolved or matured and leakage is visually apparent. 2 How should this bird be treated? Correction of a crop burn cannot be undertaken until all necrotic or devitalized tissue has recovered or died, so that vital tissue can be surgically separated from dead tissue. The bird should have an empty crop at the time of planned surgery. By this stage, adhesions will have formed between the crop wall and the overlying skin. Following induction of anesthesia, intubation, fluid therapy, analgesia, and antimicrobials as required, the overlying skin is plucked and surgically prepared. A skin incision is extended longitudinally above and below the orifice, without incising into the crop. The adhesions between the skin and crop wall are surgically resected, and the crop defect is closed using a double inversion pattern, using an absorbable monofilament suture material (due to risk of infection tracking from within the crop to the subcuticular space). The tissue is flushed copiously and the skin is closed separately. Care is taken not to permit excessive crop stretching for a few days following surgery. 3 How can the condition be avoided? The condition is easily avoided by not heating food in a microwave or mixing well after heating and measuring the temperature of the food before feeding the birds. Further reading Forbes NA (2016) Soft tissue surgery. In: Avian Medicine, 3rd edn. (ed. J Samour) Mosby, St. Louis, pp. 294–311.
CASE 150 1 Name four drugs used to treat PDD and describe their mode of action. (1) Celecoxib: NSAID, selective COX-2 inhibitor. Most commonly used drug to treat PDD. Has been shown in limited studies to reverse clinical signs as well as pathologic lesions. (2) Tepoxalin: NSAID, combined COX-1, COX-2, and 5-lipoxygenase inhibitor. Based on a single limited study may be more effective than celecoxib in reversing clinical signs as well as pathologic lesions. (3) Cyclosporine: specific T-cell inhibitor. Very limited data show this drug to reverse clinical signs in PDD patients and to improve pathologic lesions. (4) Amantadine hydrochloride: antiviral, induces release of dopamine and norepinephrine in the brain. Has been reported to alleviate clinical signs in PDD patients with severe neurologic signs, but to be ineffective in reducing virus shedding and/or clearing the infection. 2 Name two groups of drugs commonly used as supportive therapy for patients suffering from PDD. (1) Gastrointestinal motility modifiers to enhance gastrointestinal motility. (2) Antibiotics and antifungals to treat secondary infections.
3 Is PDD a lethal disease? Not necessarily. Long-term clinical remissions and resolution of the lesions have been reported with NSAIDs and, in some cases, cyclosporine therapy, especially if treatment was initiated at an early stage of the disease. Titrating medical doses and frequency of administration based on postbarium contrast fluoroscopic assessment has been found to be far more effective than basing the latter on physical assessment or owner observations. Meloxicam has been shown to be ineffective at the dosages evaluated. Further reading Gancz AY, Clubb S, Shivaprasad HL (2010) Advanced diagnostic approaches and current management of proventricular dilatation disease. Vet Clin North Am Exot Anim Pract 13(3):471–494.
CASE 151 1 What would be the most likely differential diagnoses for this case? In any cockatiel, or similar size bird, presented with acute-onset respiratory distress, an important differential is tracheal obstruction following the inhalation of a millet seed. Patients with nonobstructive upper respiratory disease (e.g. rhinitis, sinusitis) or lower respiratory disease (pneumonia, coelomic fluid or masses, airsacculitis) present with variable respiratory rate and effort and a more progressive onset of clinical signs. Many have a palpably enlarged coelomic cavity and sometimes low body condition. 2 What initial emergency treatment and diagnostic plan would you pursue? This bird is presented with acute respiratory distress and requires immediate attention. The degree of distress will dictate the urgency of intervention. The bird should be placed immediately in an oxygen chamber. Stress must be decreased to avoid increasing the oxygen demand. The bird is premedicated with midazolam (0.5 mg/kg) and butorphanol (1 mg/kg) IM and anesthesia is induced and maintained with isoflurane or sevoflurane with 100% O2. Air sac cannula placement with a 2.0 endotracheal tube is performed as an emergency procedure. This can provide the bird with an alternative airway until the tracheal compromise is relieved. Radiographs would be required to rule out other respiratory and nonrespiratory diseases responsible for the clinical signs; however, an inhaled millet seed is not always apparent radiographically. If the feathers on the cranial neck are parted, and the trachea is transilluminated, the seed might be visualized in the cranial portion of the trachea. Alternatively, once the air sac breathing tube is in place, endoscopy with a 1.9 mm telescope will allow visualization of the tracheal lumen and bifurcation to confirm the diagnosis. 3 What treatment would be required? Treatment of tracheal obstruction by a foreign body (e.g. millet) in the cockatiel is challenging due to small patient
Answers size and limited access to the proximal trachea and syrinx. Treatment options include: • Inserting a 25- or 27-gauge needle carefully between tracheal rings just caudal to the seed, inserting a fine hypodermic needle attached to a 3 mL syringe just below the seed, then air is blown from the syringe and the seed will often pass craniad, typically lodging in the glottis, from where it may be removed with fine forceps. The procedure is repeated as needed until the millet is propelled out of the glottis. The bird should be monitored carefully during this procedure. • Inserting a 25- or 27-gauge needle carefully between tracheal rings just caudal to the seed, then passing per glottis a fine soft rubber feeding tube (e.g. 4 Fr), which in turn is attached to a suction unit. Pass the tube via the glottis into the trachea, turn on the suction, and advance the tube. The seed will often become attached to the end of the tube and may then be withdrawn from the trachea. • Removal of a millet seed from the syrinx via tracheotomy using magnification and microsurgical techniques.
CASE 152 1 List four noninvasive methods of evaluating eggs and avian embryos during incubation? (1) Candling; (2) floating eggs; (3) radiographs; (4) digital cardiac egg monitor (Buddy, Vetronic Services). The Buddy digital egg monitor shown (152) has a chicken egg in the egg holder end and the tracing of the heart rate at 269 beats per minute on the readout screen. 152
2 At what stages of incubation are the above noninvasive methods most useful? Candling is most useful to monitor fertility and early embryonic development, but not as useful for later embryonic development when the embryo fills the egg. Floating eggs is most useful in the last days of incubation when small movements of the embryo in the egg can be detected and are visible as small ripples on the
water in the floatation container. Radiographs are useful in very late-term embryo development to help evaluate bony structures and determine the position of the embryo within the egg. The Buddy digital egg monitor is useful for detecting embryonic heart beats, starting about 25% of the way through incubation. 3 Which of the above methods may be useful in determining if and when to assist a weak or malpositioned embryo in hatching, and why is each useful? All four methods can be useful. Candling can be used to locate and determine if the air cell is in the normal location in the blunt end of the egg, and to visualize the bill after it enters the air cell (internal pip). Floating eggs can be used to determine how weak or strong the embryo appears to be by its movement, but this is a very subjective measurement. Radiographs are useful to determine embryonic positioning. The Buddy digital egg monitor is useful for assessing the heart rate of the embryo. One study reported that the heart rate starts dropping as much as 24 hours before lateterm embryonic death. The heart rate can be used to determine if the embryo is healthy and slow to hatch or weak and in need of assistance to hatch. Further reading Lierz M, Gooss O, Hafez HM (2006) Noninvasive heart rate measurement using a digital egg monitor in chicken and turkey embryos. J Avian Med Surg 20(3):141–146.
CASE 153 1 What is the organ protruding from the vent? The tissue is a prolapsed phallus. In Anseriformes the resting phallus is a long blind-ending tube that lies coiled in a sac with peritoneum along the ventrolateral wall of the cloaca, like an invaginated finger of a glove. The tip of this phallus shows erythema, mucosal erosions, and swelling secondary to trauma. 2 How would you initially treat this condition? The phallus may be viable, despite the swelling and mild trauma, but the duration of the prolapse makes recurrence quite likely. The presence of potential sexual partners for the drake also makes recurrence likely as soon as the bird is returned to the flock. If the owners are willing to attempt replacement, or the bird is required for breeding, the exposed tissue is cleaned, débrided, and returned to the cloaca. Two transverse simple interrupted sutures are placed on both sides of the vent to hold the phallus in situ, without compromising defecation. Depending on the degree of damage and potential scarring, breeding may still be compromised. Supportive treatment, including analgesics and antibiotics, should be administered as needed. 3 How would you treat this condition if it recurs? Chronic phallus prolapse in male ducks may require amputation. The phallus is penetrated with absorbable 3-0 to 5-0 suture material between the fossa ejaculatoria and the sulcus phalli, and sutured with a transfixion suture pattern. The phallus is transected distal to the
Answers ligature, and the stump is reintroduced into the cloaca. Since the phallus is only a copulatory organ separated from the urinary tract, urination will not be affected. Further reading Guzman DS (2016) Avian soft tissue surgery. Vet Clin North Am Exot Anim Pract 19(1):133–157.
CASE 154 1 Name the condition. A synostosis (bridging callus) has formed between the radius and ulna. This bony bridge prevents the normal rotational motion and extension of the wing. It is most likely to occur in fractures of the distal radius and ulna. 2 How is it prevented? Synostosis occurs more commonly when radius/ulna fractures are managed with coaptation rather than with surgical fixation. Because restricted movement encourages callus formation between the bones, physical therapy should be performed every 2–3 days during coaptation. Physiotherapy should consist of passive range of motion exercises using gentle extension for each joint and holding for 30–45 seconds. Anesthesia should be used during physical therapy as necessary. Surgical fixation of radius and ulna fractures is the preferred method to avoid formation of synostosis. If despite surgical repair of both bones there is deemed to be a risk of synostosis occurring, then a fat pad (harvested fresh into saline [sterile], prior to the orthopedic surgery, from a subcutaneous site in the mid line over the old yolk sac attachment) is placed between 154b the ulna and radius at the site of risk. The bird is medicated with NSAIDs postoperatively and wing movements are encouraged from 48 hours post surgery. 3 How is it treated? If range of motion is limited by the presence of a synostosis, surgical intervention is necessary to return normal function. The site is approached from the dorsal aspect. The bony bridge may be removed using a compressed air dental drill or, in larger patients, an osteotome or rongeurs. Polypropylene mesh or a harvested fat pad from the abdominal area may be placed in the resulting channel (154b)
to discourage recurrence of the synostosis. As movement is essential to preventing recurrence, surgical separation should only be performed once a bird is healthy enough to be moved to a flight enclosure or flown frequently after a few days of postsurgical wound care. Further reading Redig PT, Ponder J (2016) Management of orthopedic issues in birds. In: Avian Medicine, 3rd edn. (ed. J Samour). Mosby, St. Louis, pp. 312–350.
CASE 155 1 What are the main changes present in the erythrocytes? The blood smear shows evidence of erythrocytes with polarized nuclei and a proportional increase in anucleate erythrocytes (erythroplastids). Avian erythrocytes are typically nucleated, but in many birds a very small proportion of erythroplastids may be encountered in the peripheral blood during routine hematology; in rare cases of disease these may comprise >40% of the circulating erythrocytes. However, there are no strong relationships between the concentration of erythroplastids and the hematocrit or with regenerative responses. 2 What are the main cytologic features used to assess signs of a regenerative response in avian blood smears? The main cytologic feature that is used to assess a regenerative response in avian blood smears is the degree of erythrocyte polychromasia, with a percentage of polychromatophilic erythrocytes counted for each blood smear. 3 What is the best anticoagulant to use to preserve avian blood for routine hematologic evaluation? While dipotassium ethylenediaminetetraacetic acid (K2EDTA) is the preferred anticoagulant for preserving cellular morphology for the majority of avian species, the blood of some bird groups such as corvids, some exotic waterfowl, ostriches (Struthio camelus), black curassows (Crax alector), black crowned cranes (Balearica pavonina), gray crowned cranes (Balearica regulorum), hornbills (Tockus alboterminatus), and brush turkeys (Alectura lathami) will hemolyze in K2EDTA. In those species where this occurs, heparin is the preferred anticoagulant. It is important to remember that heparin will not prevent thrombocyte aggregation, but clumping of thrombocytes alone does not affect the WBC count. For routine avian hematology, it is always best to make fresh blood smears at the time of collection, especially when blood is being collected from smaller birds or when the volume for analysis is limited. Further reading Clark P, Hume A, Raidal SR (2013) Erythroplastidcytosis in a Major Mitchell cockatoo. Comp Clin Pathol 22(3):539–542.
Answers CASE 156 1 Which nematodes would you consider as the most likely differential diagnoses? Capillarid nematodes such as Eucoleus dispar, Eucoleus contortus, Baruscapillaria falconis, and Capillaria tenuissima. 2 How would you confirm the presence of the parasite? Fecal sample or mucosal scraping examination allows detection of eggs or adult worms. 3 What treatment would you suggest in this case? Fenbendazole (20 mg/kg PO q24h for 5 days), febantel (30 mg/kg PO once), levamisole (10 mg/kg PO q24h for 2 days), and ivermectin (0.2 mg/kg PO, SC, IM, two dosages 10–14 days apart) have been proven effective in treating capillarid nematodes. Capillaria spp. commonly demonstrate multiple anthelmintic resistance. Post-treatment fecal examination is always recommended. Nutritional support is likely to be required if the upper gastrointestinal tract lesions are severe and lead to anorexia and regurgitation, as in this case. Capillaria spp. have a direct and indirect life cycle, with earthworms as an intermediate host. Apart from treating the infection, exclusion of the intermediate host from the environment (e.g. impervious aviary floors) or suspended flights are required. Further reading Yabsley MJ (2014) Capillarid nematodes. In: Parasitic Diseases of Wild Birds. (eds. CT Atkinson, NJ Thomas, DB Hunter) Wiley-Blackwell, Ames, pp. 463–497.
CASE 157 1 What four factors, whether using natural or artificial incubation, are important to the microenvironment surrounding an egg? The four factors important to the egg environment in the nest and, especially, in incubators are: (1) temperature of the air surrounding the egg and the temperature of anything in contact with the egg, such as the brood patch of the incubating adult bird; (2) the humidity of the air around the egg; (3) movement or rotation and orientation of the egg in the nest or in the incubator; and (4) ventilation or air movement around the egg. 2 Why change the air in incubators? Why is the incubator and room ventilation important? Does an egg need ventilation during the entire course of incubation? Initially the ventilation requirements for an egg are minimal. Early in embryonic development, the primary energy source in the developing embryo is a lactic acid pathway not involving a need for oxygen. For chicken eggs, this changes around day 4–5 of a 21-day incubation as the embryonic heart develops and there is a change to an energy pathway involving intake of oxygen and production of carbon dioxide waste gas. For most avian species this occurs about 20–25% of the way through incubation.
3 How much oxygen does a developing embryo (chicken) need in an egg during incubation? How much carbon dioxide does the developing embryo produce during incubation? During the normal 21-day incubation of a chicken egg, the developing embryo needs 4.617 liters of oxygen and will produce 3.864 liters of carbon dioxide. Thus, there is a need for adequate air flow (ventilation) in the incubator and in the room where the incubator is located. Reducing the oxygen levels in the incubator below 17% can reduce hatchability (normal oxygen levels in air are about 20%). For carbon dioxide, levels above 1% in the incubator air reduce hatchability and levels above 2% are lethal to embryos. This is most important when a large number of eggs are being incubated and all the eggs are using oxygen and producing carbon dioxide. There is a slight difference in urban air versus country air, with urban air running around 0.08% carbon dioxide versus 0.03% in country air, although this difference is probably negligible to a developing egg. A GQF incubator is shown (157a). The ventilation fans are located on the back of the top shelf (157b). A Lyon table top incubator with the ventilation fan located in the lid is shown (157c). A close-up of the ventilation fan is also shown (157d). 157a
Further reading Anderson Brown AF, Robbins GES (2002) The physical conditions needed for successful hatching. In: The New Incubation Book. Hancock House Publishers, Surrey, pp. 96–134.
Answers CASE 158 1 What is the main differential diagnosis? Psittacine beak and feather disease, caused by psittacine circovirus, results in feather loss and abnormal feather coloration, as seen in this bird. 2 What is your advice to the owner in respect of these birds? Do not move any birds in or out. Have the three young birds tested and, if negative, move them into accommodation that cannot be contaminated with circovirus. If positive, keep and retest in 30 days; if still positive after this, clinical disease will ensue, typically within months. 3 What treatment can be provided to these young birds? There is one peer reviewed published report of the clearance of circovirus from young infected but not clinically affected young parrots, using repeated doses of avian interferon. Antibiotics and antifungals might be indicated if the birds are immunosuppressed. Further reading Stanford M (2004) Interferon treatment of circovirus infection in grey parrots (Psittacus e erithacus). Vet Rec 154:435–436.
CASE 159 1 What is the lesion shown? The image shows a typical cross-section through the crop wall, including the various layers (mucosa, submucosa, muscularis, and adventitia). The arrow points towards a myenteric ganglion on the adventitial surface. The ganglion is heavily infiltrated by small, dark-staining, mononuclear cells. The image shows lymphoplasmacytic myenteric ganglioneuritis. 2 In what disease is this lesion characteristic? This lesion is considered pathognomonic for proventricular dilatation disease. Note that proventricular dilatation disease and avian bornavirus infection are not synonymous, as some birds may be subclinical carriers of these viruses. 3 What are the key points for collection and preparation of a crop biopsy? Obtaining a biopsy of sufficient size (e.g. 12 × 8 mm). The biopsy should include a prominent blood vessel along its long axis, as this will increase the probability of including sufficient nervous tissue in the sample, and thus the sensitivity of the test. Following fixation in 10% buffered formalin for at least 24 hours, the biopsy should be carefully sliced perpendicular to its long axis to produce as many thin slices (approximately 1 mm thick) as possible. Preparing 6–10 such sections is recommended. A small tissue sample should be kept without fixation for bornavirus real-time PCR testing. Further reading Gancz AY, Clubb S, Shivaprasad HL (2010) Advanced diagnostic approaches and current management of proventricular dilatation disease. Vet Clin North Am Exot Anim Pract 13(3):471–494.
CASE 160 1 What dermatologic physical examination findings are present? The image shows a budgerigar with proliferative lesions of the rhinotheca and cere. The lesions are characteristically ‘honeycombed’ in appearance. 2 What organism is associated with this physical examination finding, and what diagnostic tests would aid in identification? Knemidocoptes (Cnemidicoptes) pilae is a burrowing mite in the order Sarcoptiformes that is classically associated with this presentation. A skin scraping, as traditionally performed in mammals, and microscopic examination would aid in identification of the mite. As a sarcoptiform mite, the organism would be round to oval in shape; adults have four legs with five segments on each leg. 3 How would you treat this bird? Treatment for the primary cause of the lesions is focused on antiparasitic agents; however, some birds with severe lesions may require antibiotics to treat secondary bacterial infection or general supportive care (analgesics, rehydration, assisted feeding). Antiparasitic agents that have been reported include ivermectin and other avermectins (moxidectin, selamectin) and topical paraffin oil. It is vital that all in-contact birds are treated, as subclinical carriers may subsequently reinfect this bird. Treatment involves weekly application for 4–6 weeks. Ivermectin is dosed at 200 µg/kg and in itself has a very wide safety margin; however, ivermectin is typically diluted in propylene glycol, which can cause toxic effects. It is safest to use a diluted aqueous formulation (e.g. aqueous oral sheep drench) and administer by mouth, rather than the propylene glycol formulation topically. Further reading Schmidt RE, Lightfoot TL (2006) Integument. In: Clinical Avian Medicine, Vol. 1. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 395–410.
CASE 161 1 What abnormalities of the droppings are present? Lipid droplets, voluminous feces, and polyuria. 2 What is the most likely underlying cause? Exocrine pancreatic insufficiency (EPI). EPI in parrots is not a common presentation. It can arise after any inflammatory insult caused by an infectious agent or immune-mediated condition, or, alternatively, by toxins, leading to pancreatic atrophy. Viral diseases that also affect the pancreas are paramyxovirus 3, avian polyomavirus, adenoviruses, and psittacine herpesvirus 1; these are all known to have affinity for the pancreas in parrots. Bacteria, such as Chlamydia psittaci and many others, can affect the pancreas as an extension of systemic disease. Zinc, a common toxin of caged birds, can cause pancreatic acinar degranulation. Cyclopiazonic acid, a toxin produced
Answers by fungi, such as Penicillium spp., Aspergillus versicolor, A. oryzae, A. flavus, and A. tamari, causes degeneration and necrosis of the exocrine pancreas. 3 What simple fecal test can be 161b performed to confirm the diagnosis? Lugol’s iodine test (161b). In EPI cases, undigested starch will be present in the feces; adding Lugol’s solution (iodine disinfectant solutions can be used instead) will result in a dark-blue-toblack color change (A). A healthy bird’s (A) (B) feces should be used as control (B). Further reading Lumeij JT (1994) Gastroenterology. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, p. 513.
CASE 162 1 What are some of the clinical indications for esophagostomy tube placement in avian patients (162a)? Esophagostomy tube placement is indicated in cases of severe trauma or disease involving the beak, as well as diseases of the oropharynx, proximal esophagus, or crop, such as abscesses and neoplasms. They are not recommended for regurgitating or vomiting individuals or for patients with respiratory disease. Esophagostomy tubes may also be used to bypass the crop in cases of severe crop trauma such as burn injury, crop laceration, or refractory crop dysfunction. They can also prove useful postoperatively in 162b proventriculotomy patients. The technique is also useful in patients who are well trained and will tolerate tube use without restraint; where tube use for medication, feeding, or fluids is required four or more times a day; or where the patient would otherwise be extremely stressed by physical restraint for gavage tube administration. 2 Are esophagostomy tubes generally well tolerated in birds? Yes. In a case series of 18 birds of prey, esophagostomy tubes were well tolerated in all but two patients. A cloth cover may be fitted over the bird’s back, with ties joining from right shoulder to left caudal and left shoulder to right caudal, to prevent the bird interfering with the tube end when not in use (162b).
3 When preparing to place an esophagostomy tube in raptorial species, at what level do you aim to place the distal tube end, and why? The distal tube end should be positioned at the cranial proventricular level. If it is further distal, the sensation of the tube within the proventriculus may trigger the bird to attempt to ‘cast up’ the tube, as it naturally would a ‘casting’ (i.e. the indigestible part of its diet). Further reading Huynh M, Sabater M, Brandao J et al. (2014) Use of an esophagostomy tube as a method of nutritional management in raptors: a case series. J Avian Med Surg 28(1):24–30.
CASE 163 1 What abnormalities can be seen in the histologic section? The histologic features show distension at the base of the glands, with pink proteinaceous fluid and sloughing of glandular epithelial cells with karyomegaly and basophilic intranuclear inclusions consistent with an acute DNA virus infection. 2 What etiologic agents should be considered? Avian polyomavirus is the most likely cause of the inclusions but adenovirus, herpesvirus, and finch circovirus should also be considered as possibilities. 3 What other diagnostic tests should be performed to confirm a specific etiologic diagnosis? Similar intranuclear inclusions were also seen in the liver and this case was confirmed positive for avian polyomavirus infection by PCR testing. Further reading Raidal SR (2012) Avian circovirus and polyomavirus diseases. In: Fowler’s Zoo and Wild Animal Medicine, Current Therapy, Vol. 7. (eds. RE Miller, ME Fowler) Elsevier Saunders, St. Louis, pp. 297–303.
CASE 164 1 What are the main differential diagnoses? Hepatic granulomas and abscesses can be found in several avian diseases caused by viruses (avian reovirus), bacteria (Mycobacterium, Yersinia, E. coli, Salmonella spp., Staphylococcus spp., Streptococcus spp.), fungi (Aspergillus spp.), or parasites (coccidia, ascaridia). 2 What complementary examination would you perform? Liver impression smears were prepared for cytology and Gram stain. While cytology confirmed a large number of unidentified bacteria, Gram stain showed a large number of small, gramnegative, and bipolar stained bacteria, suggestive of Yersinia pseudotuberculosis (164b). The diagnosis was confirmed by PCR testing.
Answers 3 How would you prevent this disease? Access by wild birds or vermin, such as cockroaches, rodents, and flies, into the aviaries of susceptible birds must be controlled as much as possible. Soil should be changed periodically and water should always be kept clean. Potential sources of stress, such as overcrowding and any other environmental or social stressors, should be investigated and addressed.
Further reading Allchurch AF (2003) Yersiniosis. In: Zoo and Wild Animal Medicine, 5th edn. (eds. RE Miller, MR Fowler) Elsevier, St. Louis, pp.724–727.
CASE 165 1 Describe the anatomic entry points for a triple-entry salpingohysterectomy. The first entry point is made just cranial to the pubis bone and ventral to the flexor cruris medialis muscle (165b, 2). Following insertion of a telescope through this incision, a second port is created under endoscopic guidance, caudal to the pubis bone and ventral to the flexor cruris medialis muscle (165b, 3; white arrow). The third entry point is made immediately caudal to the last rib (165b, 1; black arrow) and ventral to the flexor cruris medialis muscle (165b, m). 165b
2 What structures, labeled (1), (2), and (3) in image 165a, is the uterus (4) closely associated with and that need to be avoided during salpingohysterectomy? The immature uterus is closely associated with the kidney (1), the ureter (2),
and the renal vein (3). Therefore, it is important to provide traction and keep the reproductive tract elevated away from these structures during dissection. In larger, mature females the reproductive tract may be so large that intracorporeal manipulationbecomes difficult. 3 What are the limitations and contraindications of salpingohysterectomy in birds? Apart from the size limitations of avian patients and surgical and anesthetic complications, salpingohysterectomy does not involve removal of the ovary. In contrast to salpingohysterectomy, ovariectomy still remains a high-risk procedure in birds, and is reserved for cases where severe disease is present and/or euthanasia is being considered. Ovariectomy is rarely, if ever, considered an elective procedure in companion birds. Salpingohysterectomy does not appear to prevent ovulation and therefore carries a risk of future egg yolk coelomitis, particularly in high fecundity species like chickens. Salpingohysterectomy should therefore not be a recommended treatment option for chronic egg laying birds or high fecundity species, unless additional steps are taken to prevent ovulation. The procedure should be reserved for cases of nonovarian reproductive tract pathology and, if performed, may need to be coupled with long-term GnRH agonist administration. Further reading Hernandez-Divers SJ, Stahl S, Wilson GH et al. (2007) Endoscopic orchidectomy and salpingohysterectomy of pigeons (Columba livia): an avian model for minimally invasive endosurgery. J Avian Med Surg 21(1):22–37.
CASE 166 1 What is the normal position for the embryo when hatching? In the normal position the head moves from between the legs in the narrow end of the egg to under the right wing in the wide end 166c of the egg. The egg tooth on the bill is pointed at the air cell membrane (166c). 2 Identify the number of this malposition and the prognosis for the embryo. Malposition 2 (166a). In this position, characterized by the head being located in the small end of the egg, the entire embryo is upside down in the egg as compared to normal orientation. The feet and yolk sac are located up near the air cell. If the embryo succeeds in pipping (breaking through the shell), a normal hatch can happen. About 50% of embryos in this position will die.
Answers In malposition 6 (166b), the head is over rather than under the right wing. This position is likely to result in a live hatch with few complications. 3 Describe the effect each of the other types of malpositioning can have on hatching death. The other types of malposition are as follows: • Malposition 1: the embryo’s head is found between the thighs; this is a normal position early in incubation. However, during the last third of incubation, the embryo should move its head up and under the right wing. Malposition 1 is always fatal; it can be associated with above normal incubation temperatures. • Malposition 3: this occurs when the chick rotates its head under the left wing instead of the right wing. This malposition is nearly always lethal and is associated with malnutrition in laying females, high incubation temperatures, or improper positioning of the egg during incubation. • Malposition 4: the body is rotated in the long axis of the egg. The head is, therefore, away from the air cell and along the side of the egg. Without assistance, this malposition is often fatal as the embryo never breaks through to breathe. • Malposition 5: this occurs when the feet are located over the head. Because of this malposition, the legs are not located properly to kick and cause the body to rotate as the chick is cutting out. Unless hatching is assisted, the results will often prove fatal. • Malposition 7: this occurs when the embryo is small or the egg is spherical. The embryo is found lying crosswise in the egg instead of in the normal orientation with the head up near the air cell. This malposition is often fatal. Further reading Clubb S, Phillips A (1992) Psittacine embryonic mortality. In: Psittacine Aviculture, Perspectives, Techniques and Research. (eds. R Schubot, KJ Clubb, SL Clubb) Aviculture Breeding and Research Center, Laxahatchee, pp. 10-1 to 10-9. Olsen GH (2000) Embryological considerations. In: Manual of Avian Medicine. (eds. GH Olsen, SE Orosz) Mosby, St. Louis, pp. 189–212.
CASE 167 1 What are the contraindications for tube feeding in the avian patient? The most important contraindication for tube feeding is lack of experience, since improper tube feeding can result in aspiration and potentially patient death. In general terms, the largest feeding tube (with the biggest roundest end) should be used, as the chances of esophageal damage or gavage into the trachea are reduced. Additional contraindications for tube feeding include birds that are regurgitating or unable to keep their heads elevated. Tube feeding should also not be performed until the patient has been rehydrated.
2 What is the estimated crop volume? Estimated crop volume is 20–50 mL/kg (2–5%) of body weight, varying between species and with respect to age. Generally, administration commences with a small volume (1–1.5% of body weight) and once tolerated increased to 3–5%. Juveniles tend to have a proportionately larger crop capacity than adults. Owls, toucans, gulls, and penguins have no crop and hence food should be administered more slowly. Irrespective of frequency and volume of feeding, the patient should be weighed first thing each morning (prior to feeding or medicating) to ensure that weight is being maintained or increased. If the latter is not being achieved, volume fed or frequency of feeding must be increased. 3 List the potential complications of tube feeding. Aspiration and possible death are potential complications of tube feeding. If the tube is passed forcefully, it may lacerate the oropharynx or perforate the crop. If continued, food may be injected through the laceration and into the surrounding tissue, potentially causing lifethreatening cellulitis, or into the clavicular air sac resulting in airsacculitis and possible aspiration pneumonia. Further reading
Roset K (2013) Clinical technique: tube feeding the avian patient. J Exot Pet Med 21(2): 149–157.
CASE 168 1 What will you tell your client? You should tell your client that the egg is fertile. The blood vessels indicate fertility. This egg is viable. Lack of blood vessels would indicate a nonfertile or an infected or diseased egg. 2 By what day should you see blood vessels in a candled psittacine egg? By day 3 to 4 you should see blood vessels in a healthy fertilized psittacine egg. While blood vessel development can occur later, it is rarely apparent before day 3 to 4. 3 What do you see in this egg besides blood vessels? Besides blood vessels there is a tiny embryo visible in this egg. If the embryo dies, candling will reveal a blood ring. A blood ring indicates a dead and probably genetically abnormal or diseased embryo from a fertilized egg. It can also indicate early embryonic loss due to questionable incubation parameters, including improper temperature, humidity, rotation, rough handling and excessive vibrations, or poor ventilation. Further reading Romagnano A (2005) Reproduction and paediatrics. In: BSAVA Manual of Psittacine Birds, 2nd edn. (eds. N Harcourt-Brown, JR Chitty). British Small Animal Veterinary Association, Gloucester, pp. 222–233.
Answers CASE 169 1 What disease condition is affecting this young rhea? The changes seen in the ribcage of this rhea are consistent with rickets. The ribs are deformed and there are rounded, white cartilaginous nodules present at the junctions of the vertebral and sternal ribs (costochondral junctions), as well as at sites of pathologic fractures. 2 Describe the pathogenesis of the lesions shown. Rickets is a nutritional disease of young growing birds and can be caused by absolute deficiencies of vitamin D, calcium, or phosphorus, or by imbalances in the ratio of calcium to phosphorus in the diet. Vitamin D deficiency results in reduced gastrointestinal calcium absorption, increased secretion of parathyroid hormone from hyperplastic parathyroid glands, and failure of mineralization of developing bone, particularly in the hypertrophic zone of the epiphyseal plate. Calcium and phosphorus deficiencies result in similar lesions; histopathology of bone may help differentiate among the three main causes of rickets. 3 What management actions should be taken to reduce disease associated with the condition shown? Evaluation and correction of dietary imbalances are required to address the cause of rickets and other metabolic bone diseases. This may require a nutritional evaluation of the diet or testing of feeds to ensure that the listed nutritional composition is correct. In rare cases, malabsorption from gastrointestinal disease may mimic nutritional deficiency. Injection with vitamin D3 and calcium supplementation may be used therapeutically in addition to correction of the diet. Further reading Klasing KC (2013) Nutritional disease. In: Diseases of Poultry, 13th edn. (eds. DA Swayne, JR Glisson, LR McDougald et al.) Wiley-Blackwell, Ames, pp. 1205–1232.
CASE 170 1 What is the main concern in this bird? A bird’s crop is not a stomach, being more akin to a shopping basket. The crop will normally start to empty soon after feeding, being empty within 6–8 hours. There is no acid or enzyme to prevent putrefaction and any meat is being held close to 41°C (105.8°F). The meat will rapidly go off, producing toxins that enter the blood stream rapidly, creating a potentially critical situation. This condition is termed ‘sour crop’. 2 When is this clinical presentation most likely to occur? The situation is most likely to arise when a bird that is in very thin (low) condition is given an over full crop. Most commonly this is when a bird first enters (kills for the first time). The falconer may well have had to reduce the bird’s weight further and further to make the bird keener to catch and kill quarry, and the bird may have had to fly particularly hard to make that kill. The falconer may be tempted to reward
the bird well for making its first kill, allowing it to consume a large crop of food. The same scenario can arise if a bird is recovered in very low condition having been ‘absent without leave’ for a few days; the falconer gives a large meal in an attempt to increase the bird’s weight quickly. 3 What treatment is recommended? Such patients are far sicker than they appear. They are emergencies and must be provided with critical care irrespective of the time of day. The crop must be emptied and flushed out, and fluid therapy and antibiotics should be provided. There are a number of ways of emptying the crop. Manual retrieval from the crop to the mouth is long-winded and stressful. The quickest, most efficient, and stress free method is indicated (i.e. a brief gaseous anesthetic for ingluviotomy to empty and then saline flush the crop). If by this point the patient is not sufficiently stable for prolonged anesthesia (to facilitate surgical closure), then repair is delayed until the following day when the patient is likely to be more stable. Further reading Forbes NA (2015) Raptor nutrition masterclass. In: Proceedings International Conference on Avian, Herpetological and Exotic Mammal Medicine, Paris, pp. 33–36.
CASE 171 1 List the main differential diagnoses for this lesion. The top differential diagnoses are squamous cell carcinoma (SCC), papillomatosis, and poxvirus. Other less likely differentials include mycobacteriosis, trichomoniasis, severe hypovitaminosis A with secondary infection, fungal disease, other neoplasia, or primary bacterial infection. 2 List diagnostic tests that would be appropriate to aid in the diagnosis of this lesion. Removal of the superficial plaque with a biopsy of deeper tissues is the best approach to reaching a diagnosis. Acid-fast staining could be helpful to rule out mycobacterial organisms. Cytologic examination (particularly saline wet mount or Gram stain) of underlying exudate may also provide additional information. Fungal or bacterial culture and sensitivity could be considered to determine further information about potential secondary infections. CT could be considered to better assess the nasal passages and extent of disease. 3 Discuss likely progression timeline, treatment options, and prognosis. These lesions are generally slow/chronic in progression, although poxvirus can progress more rapidly. This bird was determined to have a SCC on deep tissue biopsy. The ideal treatment for this lesion is complete surgical excision. Due to the location and extent of disease, complete excision is unlikely and adjunct therapy should be considered. Adjunct therapies to treat oral SCC in avian patients include intralesional chemotherapy, cryotherapy, radiation therapy, NSAIDs,
Answers and phototherapy. The prognosis is good in the case of complete surgical excision (unlikely). Recurrence is likely in the case of incomplete surgical resection, but adjunct therapy may slow progression of the lesion. Further reading Zehnder A, Graham J, Reavill D et al. (2016) Neoplastic diseases in avian species. In: Current Therapy in Avian Medicine and Practice. (ed. BL Speer) Elsevier, St. Louis, pp. 107–141.
CASE 172 1 Describe the surgical approach for proventriculotomy and ventriculotomy. The left lateral tranverse coeliotomy approach preferably or the ventral midline with flap coeliotomy approach is used to access the proventriculus and ventriculus. The suspensory structures must be dissected bluntly to retract the proventriculus caudally. Stay sutures are placed in the wall of the ventriculus to exteriorize both organs. The proventriculotomy is initiated at the dorsal isthmus (junction between the ventriculus and the proventriculus) and extended cranially as needed. The ventriculus may be accessed through a proventriculotomy preferably or through a ventriculotomy through the caudoventral thin muscle. This part of the ventriculus is located just caudal to the caudal border of the sternum and is easily accessed for ventriculotomy. 2 What precautions are needed during these procedures? When this incision is made, gastrointestinal fluid might escape the incision and contaminate the coelom. To prevent this happening, exteriorize the ventriculus as much as possible, using stay sutures placed in the lateral tendinous fascia, and then pack off as much as possible around the incision site with laparotomy pads or gauze. The proventriculus is fragile and might tear if manipulated with toothed forceps or if stay sutures are placed. At the moment of incision, suction should be available and positioned adjacent to the incision. As soon as an incision is created, suction is used to remove all fluid from the gut lumen. 3 Describe how would you close the surgical incisions in these organs. The proventriculotomy or isthmus incision in most common companion avian species is closed with a fine 4-0 to 6-0 monofilament absorbable material on a small atraumatic taper needle using a simple continuous pattern with a second inverting continuous pattern. The normal isthmus incision site can be covered by caudal apices of the right liver lobe. Following proventricular closure this lobe of the liver is sutured down over the repaired incision, to adhese over the incision and reduce the risk of breakdown. The ventriculus is closed with a simple interrupted pattern using a 3-0 to 5-0 absorbable suture. The placement of collagen patches to cover the site of the proventriculotomy, or a coelomic fat patch over the ventriculotomy site, does not reduce the risk of wound dehiscence and is not recommended.
Guzman DS (2016) Avian soft tissue surgery. Vet Clin North Am Exot Anim Pract 19(1): 133–157.
CASE 173 1 What is the currently preferred anesthetic gas for avian species, and why? Isoflurane is currently the preferred choice for avian anesthesia due to its low relative cost, comparatively rapid induction and recovery, low blood solubility, and minimal metabolism. 2 When using isoflurane for raptor anesthesia, what undesirable side-effects may be observed? In addition to causing dose-dependent cardiopulmonary depression, isoflurane may cause cardiac arrhythmias. Cardiac arrhythmias, with seconddegree heart block being most prevalent, have been noted in 35–75% of bald eagles anesthetized with isoflurane. In one study, they occurred during induction and recovery in 80% of the cases. Catecholamine release was suspected to be the cause. Cardiac arrhythmias are also commonly detected in other avian species such as Pekin ducks and pigeons, but many authors feel they are more common in raptor species. 3 What are the pros and cons of using sevoflurane? Sevoflurane has better solubility than isoflurane and this allows for faster induction and recovery, as well as more rapid changes in anesthetic depth. In pigeons and bald eagles, induction and recovery times were more rapid with sevoflurane (pigeons: 95 ± 9 sec; bald eagles: 166.1 ± 16.5 sec) than with isoflurane (pigeons: 154 ± 12 sec; bald eagles: 200.3 ± 16.5 sec). In bald eagles, temperature, heart rate, and blood pressure were significantly higher with isoflurane. In red-tailed hawks, only the time to visual tracking was faster with sevoflurane compared with isoflurane. Sevoflurane has a less irritating smell than isoflurane, which may reduce stress and help prevent struggling during mask induction. Further reading Aguilar RF, Smith VE, Ogburn P et al. (1995) Arrhythmias associated with isoflurane anesthesia in bald eagles (Haliaeetus leucocephalus). J Zoo Wildlife Med 26(4):508–516. Hawkins MG, Zehnder AM, Pascoe PJ (2014) Cagebirds. In: Zoo Animal and Wildlife Immobilization and Anesthesia, 2nd edn. (eds. G West, D Heard, N Caulkett) WileyBlackwell, Ames, pp. 299–434. Joyner PH, Jones MP, Ward D et al. (2008) Induction and recovery characteristics and cardiopulmonary effects of sevoflurane and isoflurane in bald eagles. Am J Vet Res 69(1):13–22. Quandt JE, Greenacre CB (1999) Sevoflurane anesthesia in psittacines. J Zoo Wildlife Med 30(2):308–309.
Answers CASE 174 1 When is the air cell formed? The air cell is the light colored area of the inside of the egg, which forms shortly after laying. Eggs are at the body temperature of the laying female bird and cool down to environmental or ambient temperature after laying. As the egg cools, the contents shrink and air is drawn into the egg through the porous shell. 2 Where is it located in most eggs, and why is it located there? The air cell usually forms in the wide or blunt end of the egg because this is the end of the egg normally orientated upwards when the egg is resting in a cup-shaped nest. 3 What function does the air cell perform during the hatching process? The air cell functions in hatching during the first part of the hatching process, termed the internal pip. This is when the bill of the embryo breaks through the air cell membrane into the air cell itself, and the respiratory system of the embryo begins functioning for the first time by breathing the air in the air cell. Often the embryo will vocalize for the first time when this occurs. Further reading Olsen GH (2000) Embryological considerations. In: Manual of Avian Medicine. (eds. GHOlsen, SE Orosz) Mosby, St. Louis, pp. 189–212.
CASE 175 1 What is inappropriate about this initial pin placement? The IM pin was retrograded into the humero-ulnar joint space. This joint does not tolerate insult and damage by an IM pin retrograded into it through either an ulna or humerus is very likely to cause complications (i.e. 175b postoperative joint ankyloses and loss of flight). It is not possible to retrograde an IM pin through the ulna without damaging either joint. 2 What is the recommended technique for pin placement? The IM pin should be driven normograde, entering the caudal ulna between the insertions of the 3rd and 4th secondary feathers from medial (i.e. count from the elbow laterally) so as to avoid the elbow joint (see intraoperative image, 175b). This technique is made possible by the natural curvature of the proximal ulna, as present in most species.
3 What final construct would you use to repair this type of fracture? A tie-in ESF–IM pin in the ulna and an IM pin in the radius driven normograde through the distal fragment. In this fracture, an alternative repair would be to pin the radius first, passing a pin from the fracture site, normograde through the distal radius (which does not interfere with the carpal joint), then after reducing the fracture, retrograde back into the proximal radius. Once this is done the ulna is pulled back into good alignment. So long as there are no longitudinal fissures running down the ulna fragments, the ulna may be stabilized with two ESF pins in each of the proximal and distal segments, on the dorsal aspect. All four pins are then joined with a connecting bar. Further reading Redig PT, Cruz L (2008) Fractures. In: Avian Medicine, 2nd edn. (ed. J Samour) Mosby, St. Louis, pp. 215–248.
CASE 176 1 Which parasite would you consider as the etiologic agent based on the information provided? Syngamus spp., also known as gape worm. 2 If you decide to perform a tracheoscopy, what anatomic considerations should you consider in this species? In many crane species, the trachea is not straight and has multiple loops extending into the sternum to enhance their vocalization. This makes tracheoscopy in these species very difficult. 3 What treatment and control method would you recommend to the owner to reduce the prevalence in his collection of cranes? Benzimidazole anthelmintics such as fenbendazole (50–100 mg/kg PO daily for 5 days, repeated after 14 days) have been demonstrated to be effective. Ivermectin (0.2 mg/kg IM, SC, PO, two dosages 10–14 days apart) has also shown variable success. Avoid overcrowding; rear young birds on clean pasture (netted to prevent feral bird access). Avoid heavily contaminated paddocks. Syngamus spp. have direct and indirect life cycles. Earthworms act as intermediate hosts in the indirect life cycle, and play a role in the persistence of the environmental infection, as the third-stage larvae can survive in the earthworms, disappearing underground to reappear sometimes months later and, once ingested, causing disease again. Pasture rotation using a nonavian grazing species may lessen the impact of earthworms in their reservoir role. Alternatively, having an impervious substrate (concrete or plastic sheeting), covered with shallow soil or turf, could prevent earthworms burrowing and coming back up later. In the event of infection, the turf and soil are removed and replaced with clean material.
Answers Further reading Fernando MA, Barta JR (2014) Tracheal worms. In: Parasitic Diseases of Wild Birds. (eds. CT Atkinson, NJ Thomas, DB Hunter) Wiley-Blackwell, Ames, pp. 343–354.
CASE 177 1 Name three avian Orders that may be considered intermediate or definitive hosts for this parasite. Columbiformes and Psittaciformes have been reported as intermediate hosts while Falconiformes are considered the definitive hosts and may serve as source of infection for the intermediate hosts. 2 What clinical signs have been observed in intermediate hosts? Neurologic signs including torticollis, nystagmus, ataxia, inability to stand, and decreased proprioception. 3 What lesions would you expect during postmortem examination? Gross lesions may not be present. Encephalitis and meningitis are the most common histologic findings. Additionally, myositis has been described in some cases. Further reading Rimoldi G, Speer B, Wellehan Jr JF et al. (2013) An outbreak of Sarcocystis calchasi encephalitis in multiple psittacine species within an enclosed zoological aviary. J Vet Diagn Invest 25(6):775–781.
CASE 178 1 What diagnostic tests should be performed? Uropygial secretion cytology and culture (bacterial and fungal) should be performed. Cytology revealed an inflammatory response with cocci bacteria present. Fungal culture did not reveal any growth. Bacterial culture yielded a methicillin-resistant Staphylococcus aureus (MRSA) growth. Further testing allowed the identification of staphylococcal cassette chromosome mec type IV (community-acquired). 2 Preliminary results from the laboratory are consistent with a Staphylococcus spp. infection. What is the significance of this finding? Staphylococcal cutaneous colonization in captive psittacines is reported to be less common than in other species; nevertheless, cutaneous staphylococci were identified in 89/180 captive psittacines in one study. The most common Staphylococcus spp. were S.intermedius, S. epidermidis, and S. hominis subsp. hominis, while S. aureus was isolated in 4/113 isolates. In another study assessing the normal cutaneous flora of apparently healthy captive African grey parrots (Psittacus erithacus), budgerigars (Melopsittacus undulates), and cockatiels (Nymphicus hollandicus), positive skin cultures were identified in 52/75 birds, which allowed the identification of 89 bacterial colonies. Staphylococcus and Corynebacterium spp. were the most
common genera. Inthecurrent case, it is unclear if the MRSA was commensal or acquired from either the environment or humans to which the bird was exposed. Based on the cytologic evidence of inflammation and infection, it appears that bacterial involvement is expected. MRSA (community-acquired) associated dermatitis has been reported in a Congo African grey parrot. Ulcerative dermatitis and valvular endocarditis associated with S. aureus in a Hyacinth macaw (Anodorhynchus hyacinthinus) has also been reported. It was suggested that endocarditis associated with S. aureus septicemia was a potential complication of feather damaging behavior. 3 What are the zoonotic concerns? Not much is known about the zoonotic transmission of MRSA in companion animals. While S. aureus is considered to be mainly a human pathogen, it can be found in many animal species. Transmission of MRSA from birds to humans appears to be underreported; nevertheless, zoonotic capability should be considered and care should be taken to prevent transmission of such disease to owners and medical staff. Further reading Briscoe JA, Morris DO, Rankin SC et al. (2008) Methicillin-resistant Staphylococcus aureusassociated dermatitis in a Congo African grey parrot (Psittacus erithacus erithacus). JAvian Med Surg 22:336–343. Briscoe JA, Morris DO, Rosenthal KL et al. (2009) Evaluation of mucosal and seborrheic sites for staphylococci in two populations of captive psittacines. J Am Vet Med Assoc 234:901–905. Huynh M, Carnaccini S, Driggers T et al. (2014) Ulcerative dermatitis and valvular endocarditis associated with Staphylococcus aureus in a hyacinth macaw (Anadorhynchus hyacinthinus). Avian Dis 58:223–227. Lamb S, Sobczynski A, Starks D et al. (2014) Bacteria isolated from the skin of Congo African grey parrots (Psittacus erithacus), budgerigars (Melopsittacus undulatus), and cockatiels (Nymphicus hollandicus). J Avian Med Surg 28:275–279.
CASE 179 1 What is the structure labeled 1, and what is its function? The propatagium, a triangular fold of skin. It increases the surface area of the wing and forms the aerofoil shape. 2 Name the structure labeled 2. It is the leading edge of the propatagium and is supported by the ligament propatagialis pars longus. This ligament has a small, fleshy belly mainly attaching to the clavicle. The distal fifth of the tendon is fibrous and unyielding, but the majority of the tendon is elastic and will maintain the tension of the leading edge of the wing even when it is not fully extended, thereby keeping the aerofoil shape while flying. 3 What effect does damage to this structure have on the function of the wing, and how should it be repaired? Any injury to this area will prevent the bird from flying.
Answers When the propatagium is repaired, the elastic tendon must be found and, if damaged, must be repaired by suturing the ends together. Birds can fly well even when they have lost a significant part of the ligament provided it is repaired correctly.
CASE 180 1 What factors may lead to the development of hunger traces? Hunger traces can be identified as dark lines located transversely across one, several, or many pairs of feathers. An adrenocortical surge occurring while the flight feathers are developing will result in these lesions. Glucocorticoids strongly suppress growth and increase protein catabolism. These lesions probably reflect a short period of decreased amino acid availability during the development of the feather. 2 Taking into consideration the time at which these hunger lines were caused, what event took place in these pigeons that may explain the same signs in every one of the 10 pigeons? Leg bands are placed around the legs of pigeons at approximately 7 days of age. 3 Provide a possible explanation that could be the reason for these stress lines. To allow easier placement of the leg bands in these pigeons the fancier used a hand cream. On inspection of the cream, it turned out that it contained triamcinolone, a potent glucocorticoid. Triamcinolone is readily absorbed through the skin, resulting in high concentrations of circulating glucocorticoids, just as seen after any stressful event. The stress lines were likely caused by the triamcinolone used to place the leg bands. Fenbendazole treatment, administered to pigeons while feathers are growing, can also result in hunger traces. Further reading Westerhof I, Van den Brom WE, Mol JA et al. (1994) Sensitivity of the hypothalamic-pituitaryadrenal system of pigeons (Columba livia domestica) to suppression by dexamethasone, cortisol, and prednisolone. Avian Dis 38:435–445.
CASE 181 1 Which type of photoreceptor (cone or rod) is more numerous in the nervous layer of a nocturnal bird’s retina? Nocturnal birds, including owls, have some cones (responsible for visual acuity and color vision) but mostly rods (sensitive to the intensity of light), whereas diurnal birds have more cones than rods. 2 What is your diagnosis in this owl? Chorioretinitis: acute punctuate lesions (black dots) and chronic postinflammatory lesions (atrophic retinal changes) (white area).
3 List some potential etiologies. Chorioretinal lesions including chorioretinitis, choroiditis varying from focal pigmented areas, and generalized retinal degeneration with hyperreflectivity and synchysis scintillans are common in owls. Multiple etiologies for these lesions have been considered: trauma, toxoplasmosis, nutritional, and effects of sun on the retina. Results from a retrospective study of ocular findings in tawny owls (Strix aluco) demonstrated that cicatricial retinal lesions were not associated with high titers of antibodies to Toxoplasma spp., but correlated with those observed in humans with ocular injuries secondary to high-speed blunt trauma. In canaries, tachyzoites of T. gondii were confirmed in the choroid, vitreous, lens, and nerve layer of the retina of birds showing severe choroiditis, focal necrosis, and retinal detachment. Further reading Williams DL, González Villavincencio CM, Wilson S (2006) Chronic ocular lesions in tawny owls (Strix aluco) injured by road traffic. Vet Rec 159:148–153.
CASE 182 1 Based on the history and clinical presentation, what are the differential diagnoses? Fungal pneumonia and/or airsacculitis (e.g. Aspergillus spp.); bacterial pneumonia and/or airsacculitis; bacterial or fungal tracheitis; aspiration pneumonia; parasitic airsacculitis. 2 What diagnostic tests would you perform to confirm the diagnosis? Survey radiography (ventrodorsal and laterolateral projections); hematology and plasma chemistry panel; coelomic endoscopic examination; fecal parasite examination. 3 On direct fecal examination using 0.9% NaCl, numerous thick-shelled embryonated ova could be observed (182, ×400). Can you identify the ova in the fecal preparation? The ova are from Serratospiculum seurati, a nematode commonly (65%) found in falcons in the Middle East. Several arthropods (e.g.beetles) have been identified as intermediate hosts of S. seurati. The adult worms are commonly found in the air sacs, resulting in the clinical signs observed in this bird. Further reading Zucca P (2008) Infectious diseases, parasites, nematodes. In: Avian Medicine, 2nd edn. (ed. J Samour). Elsevier, St. Louis, p. 330–336.
CASE 183 1 What are the most commonly used methods for semen collection in birds? Which method applied in Falconiformes uses males imprinted onto the handlers to
Answers collect viable semen samples? Voluntary donation, massage method, and electroejaculation methods. The voluntary donation method is used in Falconiformes to collect viable semen samples. 2 What prompted falconers, primarily in the USA, to develop methods for semen collection and artificial insemination in raptors? Which organization was at the forefront in the development of artificial breeding techniques in falcons? The decline in the population of certain North American raptors such as the peregrine falcon (Falco peregrinus) prompted falconers in the USA to develop artificial breeding techniques in order to maximize the number of captive bred falcons suitable for release into strategic locations throughout the USA. The organization at the forefront was the The Peregrine Fund under the umbrella of Cornell University, Ithaca, New York, USA. 3 What is the preferred method of semen collection in most Passeriformes, as shown in this house sparrow (Passer domesticus) (183) and similar to that used in budgerigars (Melopsittacus undulatus)? What anatomic structure facilitatessemen collection in the house sparrow? The massage method. The seminal glomus facilitates semen collection in the house sparrow. These are paired structures located on both sides of the cloaca. The seminal glomus is formed by multiple convolutions of the terminal sections of the vas deferens located on either side of the proctodeum. Further reading Samour J (2004) Semen collection, spermatozoa cryopreservation and artificial insemination in non-domesticated birds. J Avian Med Surg 18(4):219–223.
CASE 184 1 Which drugs are commonly administered by intracameral injections, and what are the potential complications of this route of administration? Different drugs commonly administered into the anterior chamber of the eye are viscoelastic substances to maintain the anterior chamber pressure, adrenalin to control iris hemorrhage or induce mydriasis, tissue plasminogen activator to manage anterior and/or posterior chamber fibrin formation or carbachol to achieve myosis, and mydriatics such as D-tubocurarine. D-tubocurarine provokes a consistent moderate to maximal mydriasis in pigeons and several raptor species. Potential complications of intracameral injections are: structural damage, hyphema, intraocular pressure increase, infectious uveitis, and systemic effects. Few complications have been reported with anterior chamber paracentesis in humans and complications in birds have not been studied. 2 When does a clinician induce mydriasis in birds? Mydriasis allows posterior segment visual examination and surgery. A high percentage of raptors admitted
into rehabilitation centers because of flight trauma present with abnormalities involving the posterior segment of the eye, which may preclude their successful release. 3 What alternatives may be used to induce mydriasis in birds? Variable mydriasis can be fairly consistently achieved under general anesthesia. In raptors, shortacting anesthesia (ketamine hydrochloride and xylazine) provokes mydriasis. Air sac perfusion anesthesia has been reported to be successful in inducing mydriasis in pigeons, but appears not to achieve this in cockatoos. Topical parasympatholytic agents are ineffective due to the predominance of striated muscular fibers in the avian iris. The iris muscles may be partially paralyzed by neuromuscular paralyzing agents. Topical rocuronium bromide provokes mydriasis in European kestrels (Falco tinnunculus), common buzzards (Buteo buteo), little owls (Athene noctua), tawny owls (Strix aluco), and Hispaniolan Amazon parrots (Amazona ventralis). Topical vecuronium bromide was effective in kestrels (Falco tinnunculus), citron-crested and sulphur-crested cockatoos (Cacatua sulphurea citrinocristata and Cacatua galerita), African grey parrots (Psittacus erithacus), and bluefronted Amazon parrots (Amazona aestiva), although Amazon parrots showed mild transitory systemic side-effects. However, topical vecuronium bromide was not effective at tested doses in South African black-footed penguins (Spheniscus demersus). A topical combination of atropine, phenilephrine, and vecuronium bromide was effective in double-crested cormorants (Phalacrocorax auritus). Topical D-tubocurarine induced mydriasis in some avian species (e.g. pigeons [Columba livia domestica]) but not in others. Topical alcuronium chloride resulted in mydriasis in kestrels (Falco tinnunculus) but eyelid paralysis was observed in most of the birds and one developed neck paralysis. Topical pancuronium bromide showed inconsistent mydriasis in kestrels (Falco tinnunculus) and mild to severe systemic effects in some cockatoos (Cacatua sulphurea).
CASE 185 1 Based on the gross image, what type of testicular tumor do you suspect? Seminoma. Seminomas generally retain the shape of the testicle and are creamy white soft masses supported on a fine fibrovascular stroma. The exfoliative cytology will generally be of a dense population of round cells. 2 What is the likely cause of the clinical signs? The mass effect of the tumor displacing and compressing coelomic organs can account for the respiratory changes and contribute to the lethargy and anorexia. Nerve compression (ischiadic [sciatic] and/or pudendal) from the enlarging mass can result in a peripheral neuropathy presenting as lameness. 3 Can you determine malignancy by cytology or even by a small biopsy section? Itis usually difficult to determine the malignant potential of this tumor based solely on histologic or cytologic evaluation of the primary neoplasm.
Answers Examination of the entire testis for infiltration into the tunica albuginea, epididymis, or spermatic cord, as well as other organs, is required. Complete work up including hematology, plasma biochemistry, radiographs, and even ultrasound would be needed to stage this neoplasm. Further reading Mutinelli F, Vascellari M, Bozzato E (2006) Unilateral seminoma with multiple visceral metastases in a duck (Anas platyrhynchos). Avian Pathol 35(4):327–329.
CASE 186 1 Why is a lateral coelioscopy contraindicated in this patient for evaluation of the liver? Coelioscopic evaluation of the liver via a left or right lateral approach would create a communication between the air sac system and the hepatoperitoneal cavity, which in the presence of ascites would flood the respiratory system and potentially drown the patient or result in aspiration pneumonia. 2 What is the preferred coelioscopic approach in this patient? Ventral coelioscopy is the preferred approach in this case as the hepatoperitoneal cavity is distended with fluid, forcing the air sacs 186a laterally (186a). Therefore, a ventral midline approach permits entry into the hepatoperitoneal cavity without entering the air sacs. 3 Describe the technique for obtaining a liver biopsy in this patient. How does this differ from obtaining a biopsy via a lateral approach? A liver biopsy can be obtained from the caudal edge of the liver (186b) using 5-Fr biopsy 186b forceps. With a lateral approach, the hepatoperitoneal membrane needs to be incised with scissors prior to biopsy, as biopsy through the membrane results in greater crush artifact. Further reading Divers SJ (2010) Avian diagnostic endoscopy. Vet Clin North Am Exot Anim Pract 13(2):187–202.
CASE 187 1 How can a bird be losing body condition and yet not be losing weight? A space occupying lesion in the coelom would expand at the expense of the air sacs, as such air is replaced by soft tissue, fluid, or even gastrointestinal contents, which are heavier than air. This would result in an increase in body weight offsetting the body condition and muscle loss from the pectoral muscles. 2 What condition is this bird suffering from, and what are the three main etiologies? This bird is suffering from ascites (the diagonal fluid density line from the heart to the kidneys is characteristic). The most likely causes of ascites are heart disease causing portal hypertension, liver disease causing hypoproteinemia, or portal hypertension. Reproductive disease, gastrointestinal or renal disease (e.g. protein-losing enteropathy or nephropathy), or neoplasia in other organs of the coelomic cavitiy (e.g. spleen, pancreas) can all cause increased coelomic fluid, presenting with similar signs. 3 What steps would you take to further investigate this condition? CBC and plasma biochemistry panel; plain radiography and contrast radiography, achieved by passing a silicone feeding tube via the oropharyngeal cavity and crop directly into the proventriculus to deliver barium; coelomic ultrasound; and coelomocentesis with fluid analysis. Coelomocentesis is better performed in the ventral midline, just caudal to the point of historic yolk sac connection. Further cranially is best avoided as the liver may be enlarged, while laterally might result in penetration of the air sac, resulting ultimately in fluid being able to flow into the air sac, and may cause drowning. 187b
The barium contrast radiograph shown (187b) is of the same patient as in the question, and it confirms hepatomegaly. Ultrasound would do likewise. Further reading Krautwald-Junghanns ME, Schmidt V (2011) Special diagnostic, pathological findings. In: Diagnostic Imaging of Exotic Pets. (eds. ME Krautwald-Jinghanns, M Pees, S Reese, TTully) Schlutersche, Hannover, pp. 89–91.
Answers CASE 188 1 In what diseases is this lesion characteristic? It can be seen in birds with proventricular dilatation disease, as well as with other viral diseases causing encephalitis including West Nile virus disease, paramyxovirus disease, and other similar viral diseases. 2 Is this lesion always associated with neurologic signs in psittacines? No. This lesion is commonly seen in birds with the gastrointestinal form of proventricular dilatation disease that show no obvious neurologic signs. 3 What other histologic lesions would you expect to find in this bird? Lymphoplasmacytic myenteric ganglioneuritis; lymphoplasmacytic infiltration of medullary areas within the adrenal gland; lymphoplasmacytic myositis of the ventriculus; lymphoplasmacytic infiltration of epicedial ganglia; lymphoplasmacytic cardiomyositis; lymphoplasmacytic cuffing of peripheral nerves; perivascular cuffing in the optic nerves, choroid, ciliary body, and occasionally in the iris and pectin; retinal lymphoplasmacytic infiltration; and retinal degeneration. Further reading Gancz AY, Clubb S, Shivaprasad HL (2010) Advanced diagnostic approaches and current management of proventricular dilatation disease. Vet Clin North Am Exot Anim Pract 13(3):471–494.
CASE 189 1 How do you approach and handle an adult ostrich? Ostriches can be dangerous due to their size and their powerful legs and feet. A minimum of two people are required to handle an ostrich (189). Ostriches kick forwards, therefore a handler should not stand in front of a bird unless they already have hold of the head orneck. 189
One handler should approach the bird from the side or behind (keeping out of the way of the legs) and grasp the neck; at this point the second handler grasp the bird’s tail or wing to prevent it from swiveling round. The neck is pulled down, the head grasped, and a head cover pulled over it. Once the head is in the dark, the bird will become calmed and can be restrained safely. 2 Where are the microchip implantation sites in adults and chicks in this species? The recommended electronic microchip implantation site in birds is the left pectoral muscle. However, ratites do not possess a keel and have reduced pectoral muscle, which prevents microchip implantation in that site. The recommendation is that ostrich chicks are implanted at one day of age by placing the chip into the pipping muscle, just below the ear, on the left side (this muscle shrinks away within a few days of hatching). In adults, the microchip is implanted subcutaneously in the left side of the neck. 3 How do you differentiate between male and female ostriches? In adult (3–4 years) ostriches the male is black and the female brown. These feather color changes commence from 14 months onwards. When in breeding condition the male bird’s beak is red, as opposed to pale silvery yellow in the female. Male ostriches, like waterfowl but unlike other avian species have a phallus. Ostrich chicks may be vent sexed at 1 day of age; in experienced hands accuracy is stated to be 95%. PCR sexing can be carried out on feather samples at any age. Further reading Kummrow M (2015) Ratites: Tinamiformes and Struthioniformes, Rheiiformes, Cassuariformes. In: Fowler’s Zoo and Wild Animal Medicine, Vol. 8, 1st edn. (eds. RE Miller, ME Fowler) Elsevier/Saunders, St. Louis, pp. 75–82.
CASE 190 1 What is the most likely cause of the mass in this canary? What is another differential diagnosis for a crusty mass on the skin of a canary? The most likely cause of the mass on the wing is a feather follicle cyst (folliculoma). Avian pox lesions can look similar and cause crusty lesions, as classically described in canaries; however, they are typically on the unfeathered regions of the skin. Xanthoma may also occur on the wing tip, but is unlikely in this location. 2 The client would like to know the cause of this abnormality. What information can you share with them? Feather follicle cysts are genetically predisposed in certain lines of canaries including Norwich, Gloucester, and crested type varieties and some new color varieties. In addition, a feather follicle cyst may occur in any bird secondary to trauma to the feather follicle. 3 How would you treat this bird? Surgical resection of the abnormal feather follicle, including the dermal papilla (which the feather grows from), is required to
Answers prevent recurrence. The dermal papilla is soft (jelly-like) and located immediately in front of the inferior umbilicus (at the tip of the calamus or quill). Further reading Bowles HL, Odberg E, Harrison GJ et al. (2006) Surgical resolution of soft tissue disorders. In: Clinical Avian Medicine, Vol. 2. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 775–830.
CASE 191 1 Many veterinarians include sedation prior to IV injection of euthanasia solution. Provide examples of parenteral sedation that can be used when the owner requests to be present for the procedure. Intranasal administration or IM administration of midazolam with additional sedative agents such as dexmedetomidine or ketamine. 2 Pentobarbital may need to be administered by a route other than IV if the bird is under general anesthesia. What other routes are acceptable for the unconscious bird? Intraosseous: euthanasia drugs should not be administered via the IO route into the humerus or femur because drowning or irritation to the respiratory system may occur. IO catheters can, however, be safely placed in birds, preferably in the distal ulna or proximal tibiotarsus. Intracardiac or hepatic injection can also be used. 3 IM, SC, intrathoracic, intrapulmonary, intrathecal, and other nonvascular injections are not acceptable routes of administration for injectable euthanasia agents in awake animals. Why? Barbiturate salts and other euthanasia solutions are alkaline and considered painful at the site of injection. There is limited information available regarding the effectiveness of these nonvascular sites. Injection into an air sac or pneumatic bone may be poorly absorbed and could cause distress and drowning rather than unconsciousness. Further reading Hess L (2005) Euthanasia techniques in birds – roundtable discussion. J Avian Med Surg 19:242–245. Latimer KS, Rakich PM (1994) Necropsy examination. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, pp. 355–379. Miller EA (2000) Euthanasia of nonconventional species: zoo, wild, aquatic, and ectothermic animals. In: Minimum Standards for Wildlife Rehabilitation, 3rd edn. (ed. EA Miller) National Wildlife Rehabilitators Association, St Cloud, p. 77. Orosz S (2006) Birds. In: Guidelines for Euthanasia of Nondomestic Animals. American Association of Zoo Veterinarians, pp. 46–49. Rae M (2006) Necropsy. In: Clinical Avian Medicine, Vol. 2. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 661–678.
CASE 192 1 What is the most likely diagnosis? Serratospiculum spp. infection. 2 Describe the life cycle of this parasite. The cycle is indirect. Ova containing fully developed larvae are passed in the feces and swallowed by the intermediate hosts (beetles and other insects) in which the parasites reach the third larval stage and become infective. Once the intermediate host is eaten by a bird, larvae penetrate the proventricular and ventricular walls and migrate to the respiratory system. Female nematodes lay eggs within the air sacs, which are coughed into the mouth, swallowed, and passed in the feces. 3 What treatment options would you consider? Historically a combination of ivermectin and mechanical removal of the parasites from the air sacs using endoscopy was recommended. Research has shown that an elevated dose of ivermectin or moxidectin (1 mg/kg SC or PO, repeated in 7–14 days) is effective in killing the worms, which do not then require removal. NSAIDs and antibiotics for secondary bacterial infection are recommended. Further reading
Lloyd C (2003) Control of nematodes in captive birds. In Pract 25:198, 201–206. Samour J, Naldo J (2001) Serratospiculiasis in captive falcons in the Middle East: a review. J Avian Med Surg 15(1):2–9.
CASE 193 1 What additional diagnostic test would you perform? A direct ophthalmoscope or a slit-lamp biomicroscope facilitates the assessment of more subtle changes in the lens and lens-induced uveitis. Tonometry could be valuable to check for cataractrelated uveitis or glaucoma. Ocular ultrasonography is useful to detect retinal detachment. An electroretinogram is useful to evaluate the electrical function of the retina. 2 Which causes have been reported to provoke this condition in birds? Senile and traumatic cataracts are the most common cataracts observed in birds. Other reported causes in birds include: genetic (Yorkshire and Norwich canaries), nutritional (e.g. vitamin E deficiency in turkey embryos), electric, infectious (Marek’s disease), toxic, post uveitis, and secondary to retinal degeneration. 3 How would you treat this condition? Surgery is the only therapeutic option for cataracts. Cataract removal requires specialized microsurgery and magnification equipment as well as advanced ophthalmologic skills. Two surgical techniques have been reported in large eyes: phacoemulsification and extracapsular extraction of the lens. Aspiration with an irrigation/aspiration hand-piece or even with
Answers a cannula could be an option for species with smaller eyes. Lens-induced posttraumatic uveitis should be managed with topical and systemic anti-inflammatories (e.g. diclofenac or meloxicam) and mydriatics. Further reading Wilson D, Pettifer GR (2004) Anesthesia case of the month. Mallard undergoing phacoemulsification of a cataract. J Am Vet Med Assoc 225(5):685–688.
CASE 194 1 The energy cost of maintaining an egg’s temperature, whether by natural or artificial incubation, depends on three factors. What are these factors? The three factors important in maintaining incubation temperature in an egg are: (1) ambient temperature; (2) heat produced by the embryo at different stages of incubation – as the embryo develops in the egg, it begins to thermoregulate or begins to produce its own body heat by utilizing some of the nutrients in the egg; and (3) thermal conductivity of the egg itself; not all eggs are equal. 2 There are two types of incubation strategies used by different species of birds. Describe each strategy. The two types of incubation strategies used by birds are: (1) steady state incubation where the parent bird(s) incubate the egg almost constantly from laying the last egg (clutch completion) to hatching; and (2) intermittent incubation where the parent bird(s) will leave the nest unattended for varying lengths of time, more than required for a parental shift in incubation duties or to turn (rotate) the eggs. The parent birds may use their time away from incubation to feed, ward off intruders (nest protection), groom, or just loaf. Parental absence from the nest results in a degree of egg cooling; the quantum is affected by the duration of absence and the ambient temperature. The embryos of different species have adapted to tolerate varying degrees of cooling. Tolerance to intervals in incubation is generally greater in the last trimester. 3 When using an artificial incubation process, what type of incubation behavior (from the question above) is being duplicated with different types of incubators? Steady state incubation is usually being duplicated when eggs are placed in a forced-air incubator or a still-air incubator. These are the two most common types of incubators. The newer contact incubators have more capability to duplicate the brood patch incubation of birds and the intermittent type of natural incubation. Measuring egg temperatures in the nest or in an incubator can be done withdatalogger eggs. A sandhill crane (Gruscanadensis) plastic egg dummy,witha small data-logger in the egg to record temperature throughout incubation, is shown (194a, b).
Further reading Turner JS (2002) Maintenance of egg temperatures. In: Avian Incubation, Behavior, Environment, and Evolution. (ed. DC Deeming) Oxford University Press, Oxford, pp.119–142.
CASE 195 1 What is the most likely cause of the distended proventriculus seen in the image? How could you confirm your presumptive diagnosis? Macrorhabdus ornithogaster (gastric yeast, formerly termed megabacteria) infection. Identification of the organism can be confirmed on a nonstained or Gram-stained fecal sample in live birds or an impression smear of the proventricular mucosa at postmortem examination. 2 List other differential diagnoses. Bacterial or mycotic proventriculitis, parasitic infections such as Atoxoplasma, Isospora and Cochlosoma, avian bornavirus, toxins such as lead or other heavy metals, neoplasia, foreign body. 3 What would be the treatment plan for a canary breeder confronted with this problem? Acidify the drinking water using, for example, cider vinegar at 10 mL/L drinking water. Screen fecal samples for Macrorhabdus ornithogaster, being mindful that not all affected canaries will shed Macrorhabdus at all times. Treat affected birds with amphotericin B (1,000 mg/L in drinking water for 10 days). Further reading Rubbenstroth D, Rinder M, Stein M et al. (2013) Avian bornaviruses are widely distributed in canary birds (Serinus canaria f. domestica). Vet Microbiol 165(3-4):287–295. Sandmeier P, Coutteel P (2006) Management of canaries, finches and mynahs. In: Clinical Avian Medicine, Vol. 2. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, p. 899.
Answers CASE 196 1 What virus would most likely cause these problems in nestling Passeriformes? Avian polyomavirus (APV). 2 What findings would you expect on histopathology? How would you confirm your diagnosis? Large basophilic intranuclear inclusion bodies in many organs and often a membranous glomerulopathy. The diagnosis would be confirmed with PCR techniques. 3 What steps would be necessary to clear the virus from this collection? Stop all breeding for a complete season to minimize virus shedding. Using choanal and cloacal swabs, test all breeding birds for APV by PCR, but be aware that not all APV carriers will shed virus at all times. Eliminate all birds that test positive. Test all new birds that are introduced into the collection. Instigate a hygiene system including a closed aviary (not open to visitors) and use of foot disinfection at the entrance to the aviary, as well as disinfection of hands, food and water bowls, and tools within the aviary. Further reading Sandmeier P, Coutteel P (2006) Management of canaries, finches and mynahs. In: Clinical Avian Medicine, Vol. 2. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 892–893.
CASE 197 1 What would be your differential diagnosis for this condition? Which would be your primary differential based on the dietary history? Differential diagnoses that should be considered in this case include infectious diseases (such as West Nile virus and Newcastle disease virus), intoxication (such as heavy metal toxicity, organophosphates), and nutritional deficiencies, primarily thiamine deficiency but also calcium or vitamin D deficiency and hyperglycemia, which lead to similar signs. The primary differential in this case would be thiamine deficiency as it is a vitamin that may be low in frozen food due to limited stability. In addition, raw fish may contain thiaminase, which breaks down thiamine. 2 What specific tests would you run to rule out your primary differential? What additional body system could be affected in addition to the central nervous system if your primary suspicion is confirmed? Thiamine deficiency can be established by measuring blood thiamine levels by high performance liquid chromatography. Alternatively, erythrocyte transketolase activity may also be measured to provide a surrogate marker for thiamine status. Diet analysis to establish thiamine values may also provide evidence of this deficiency. In addition to neurologic signs, thiamine deficiency has been documented to cause cardiac arrhythmias and cardiac failure in several species including pigeons.
3 What would be your treatment plan to rectify the nutritional status of these birds? Thiamine supplementation may be provided by either enteral or parenteral routes. Doses of 2–4 mg/kg thiamine hydrochloride PO or IM twice daily have been documented to improve the clinical signs of thiamine deficiency in juvenile goshawks. While supplementation of B vitamins is generally considered safe as excess may be excreted in the urine, clinical signs and mortality following oversupplementation of certain B vitamins are documented. Therefore monitoring thiamine levels following treatment may help determine treatment efficacy andduration. Diet correction by including adult whole prey and limited storage duration prior to feeding is required to address potential additional nutritional deficiencies (such as deficiencies in calcium, phosphorus, and vitamin D). Further reading Carnarius M, Hafez HM, Henning A et al. (2008) Clinical signs and diagnosis of thiamine deficiency in juvenile goshawks (Accipiter gentilis). Vet Rec 163:215–217.
CASE 198 1 What is the tentative diagnosis? Based on the clinical signs, including lack of feather regrowth, lethargy, and obesity, hypothyroidism is highly suspected. 2 What diagnostic tests may be used to confirm the tentative diagnosis? Diagnostic tests that may be used to confirm hypothyroidism include: • Measurement of plasma or serum T4 concentration. However, a definite diagnosis of hypothyroidism cannot be based on a single low T4 result, as plasma levels may fluctuate. • A thyroid-stimulating hormone (TSH) stimulation test whereby serum or plasma T4 concentrations are measured prior to and 6 hours following IM injection of 1 IU/kg of human recombinant TSH. Hypothyroidism may be suspected based on lack of response to the administration of TSH, with T4 concentrations increasing less than 2.5 fold compared with baseline. • Thyroid scintigraphy using sodium pertechnetate Tc99m was found useful in detecting thyroid hypofunction in radiothyroidectomized cockatiels. This technique is not readily available, thus limiting its use in avian practice. • Thyroid biopsies may be collected to histologically confirm a nonfunctional thyroid gland as well as potential causes for the underlying dysfunction (e.g. thyroiditis). Such biopsies are, however, rarely performed in practice. 3 If the tentative diagnosis is confirmed, what would be the recommended treatment for this bird? In cases of confirmed hypothyroidism, treatment consists of oral L-thyroxine supplementation (20 μg/kg PO q12h).
Answers Further reading
Oglesbee BL (1992) Hypothyroidism in a scarlet macaw. J Am Vet Med Assoc 201(10): 1599–1601. Schmidt RE, Reavill DR (2008) The avian thyroid gland. Vet Clin North Am Exot Anim Pract 11(1):15–23.
CASE 199 1 Describe how this procedure should be performed. Cloacoscopy is performed with the bird in dorsal recumbency. Warm saline irrigation is provided via the ingress port of the operating sheath for visualization. Endotracheal intubation is important to protect the airway, as oral regurgitation can occur from excessive fluid administration. During irrigation, digital pressure is applied externally to the edge of the vent to prevent the infused saline leaking out, ensuring dilation of the cloacal lumen. Only a minimal amount of saline irrigation is required to provide visualization. 2 Name the labeled structures in the image shown (199), obtained during a cloacoscopy in a pigeon. 1 = coprodeum; 2 = oviductal opening; 3 = ureteral papilla on the dorsal uroproctadeal fold. 3 What difference in cloacal anatomy can be observed during cloacoscopy between a pigeon and a psittacine? Within the coprodeum, the opening to the rectum in a pigeon is on the bird’s right side and in a psittacine it is on the bird’s left side. Further reading Divers SJ (2010) Avian diagnostic endoscopy. Vet Clin North Am Exot Anim Pract 13(2):187–202.
CASE 200 1 Which one of these vitamins has been reported to cause lethal toxicity in gyrfalcons? Vitamin B6, or pyridoxine, at doses of 15 mg/kg and higher. The recommended dosage depends on protein ingestion. LD50 has not yet been documented. 2 What are the associated clinical signs? Emesis, pistachio green-colored urates, anorexia, lethargy, and death 24–36 hours post injection. 3 List three food items that naturally contain vitamin B6. Meat, liver, and kidney of prey species, and also within the digestive tract of prey items, cereal seeds, pistachio nuts, and chickpeas.
Further reading Samour J (2013) Acute toxicity after administration of high doses of vitamin B6 in falcons. Proceedings of the International Conference on Avian Herpetological and Exotic Mammal Medicine, April 2013, Wiesbaden, pp. 100–102. Scherer CS, Baker DH (2000) Excess dietary methionine markedly increases the vitamin B6 requirement of young chicks. J Nutr 130(12):3055–3058.
CASE 201 1 What are the toxic effects of avocados in birds? Effects of avocado poisoning are mainly cardiac with the presence of pericardial effusion, cardiac tamponade, and myocardial toxicity. Subcutaneous edema has also been reported in birds, in particular ostriches. 2 What is the toxin contained within avocados? The toxin contained in the avocado plant is persin. 3 What parts of the avocado are toxic? All parts of the fruit and plant (leaves, bark, seeds, fruit) are toxic, but toxicity varies between avocado varieties. Further reading Burger WP, Naudé TW, Van Rensburg IB et al. (1994) Cardiomyopathy in ostriches (Struthio camelus) due to avocado (Persea americana var. guatemalensis) intoxication. J South Afr Vet Assoc 65(3):113–118. Dumonceaux G, Harrison GJ (1994) Toxins. In: Avian Medicine: Principles and Applications. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, pp. 1030–1052. Hargis AM, Stauber E, Casteel S et al. (1989) Avocado (Persea americana) intoxication in caged birds. J Am Vet Med Assoc 194(1):64–66.
CASE 202 1 What diseases can cause a firm coelomic distension in an adult hen? Diseases that can cause a firm coelomic distension in an egg laying hen include egg-related peritonitis (ERP), lymphoid leukosis +/− involving the reproductive tract, ovarian adenocarcinoma, cystic right oviduct, egg impaction, an ectopic egg loose within the coelomic cavity, hernia, and coelomic effusion of any cause. This particular hen had ERP. The reluctance to ambulate was due to associated pain. This is a very common presentation for a hen with ERP. 2 What would be the possible treatment for each of the diseases listed above? ERP can be septic or not. If septic it is usually secondary to an E. coli diarrhea, so antibiotic treatment is indicated. While (in the USA) no antibiotics are labeled for use in egg laying hens where the eggs are to be eaten, trimethoprim sulfamethoxazole is often used and eggs discarded for at least 2 weeks after the last dose. Ideally, antibiotic use should be based on culture and after consulting
Answers with www.farad.org for withdrawal information. Note: Fluorquinolones and cephalosporins are prohibited drugs in poultry in the USA (i.e. they cannot be given to poultry in any circumstance, irrespective of life role (e.g. pet/egg or meat production). Even owner consent does not circumvent this legal restriction. The use of antibiotics in poultry aids the development of antibiotic resistant Campylobacter organisms, which would in turn make the treatment of infected humans more difficult. There are other drugs that fall under the rules of extra-label drug use (ELDU), such as sulfamethoxazole, and www.farad.org should be contacted for specific information and instructions on ELDU in poultry. Drugs used in poultry in Europe must be listed in Table 1(EU) No 37/2010. Drugs approved for use in poultry in the UK can be verified at veterinaryformulary.com. ERP can also arise concurrent with an egg or eggs loose in the coelomic cavity or a hernia, or egg impaction, necessitating surgical intervention. Radiographs or ultrasound will provide information on presence, number, and position of shelled and unshelled eggs. An attempt should be made to remove as much of the egg material as possible at the time of surgery, while appreciating that usually it cannot all be removed and surgical time must be kept to a minimum. A salpingohysterectomy is recommended for ERP or right cystic oviduct. Unfortunately, there is no treatment for lymphoid leukosis or ovarian adenocarcinoma. If coelomic effusion is present, this can be determined radiographically or by ultrasound and can be due to a variety of causes including heart disease. Further reading
Greenacre CB (2015) Reproductive diseases of the backyard hen. J Exot Pet Med 24(2): 164–171.
CASE 203 1 What is the methodology for placement of an air sac tube? While an inhalation agent is delivered via the trachea, the patient is placed in right lateral recumbency with the wings extended dorsally and the legs stretched caudally. Feathers covering a triangle formed by the cranial thigh muscles, the musculature covering the synsacrum, and the last rib are plucked. Standard aseptic preparation is performed and a clear, sterile adhesive drape is placed over the entry site. A small skin incision is performed using a scalpel blade behind the last rib or between the last two ribs, and the underlying muscle and subcutaneous tissues are bluntly dissected. The air sac is perforated using a hemostat and an air sac tube is inserted. The diameter of the air sac tube should be similar to the bird’s tracheal diameter and the length of tube inserted within the skin should not exceed one-third of the width of the coelom at the entry point. The tube must have multiple holes along its length within the air sac, such that airflow is maintained. The tube is fixed in place to
ensure that it cannot come out of the air sac using nonabsorbable suture and a Chinese finger trap knot, taking care not obstruct the tube’s lumen. 2 What are the indications to maintain anesthesia using an air sac tube? Air sac anesthesia is indicated to maintain anesthesia in patients requiring surgery or diagnostic tests involving the head, oropharyngeal cavity, eyes, or upper airway, where the presence of an endotracheal tube within the glottis will interfere with the procedure. It is also indicated where there is a partial or complete obstruction of the trachea. 3 How does air sac tube delivery of isoflurane compare with endotracheal administration of isoflurane? A study performed in sulphur-crested cockatoos (Cacatua galerita) showed both endotracheal and caudal thoracic air sac administration provided a reliable method of maintaining anesthesia and resulted in minimal alteration in respiratory function. However, transient apnea while applying caudal thoracic air sac anesthesia has been noted in a number of publications, and it is recommended that oxygen flow rates are reduced to 250 mL/kg/min and birds are ventilated with positive pressure. In chickens (Gallus gallus domesticus), measured partial pressure of carbon dioxide in expired gas (PeCO2) could not be used in a simple linear fashion to predict partial pressure of carbon dioxide in arterial blood (PaCO2) during air sac insufflation anesthesia. In that study in chickens, it was found that the PeCO2 at which apnea occurs during air sac insufflation anesthesia was not predictable. Anesthetic gas introduced via the air sac tube into the caudal thoracic air sac should naturally pass over the gas exchange surface in the paleopulmonic parabronchi. Further reading Hawkins MG, Zehnder AM, Pascoe PJ (2014) Caged birds. In: Zoo Animal and Wildlife Immobilization and Anaesthesia. (eds. G West, D Heard, N Caulkett) Wiley-Blackwell, Ames, pp. 399–405. Jaensch SM, Cullen L, Raidal SR (2001) Comparison of endotracheal, caudal thoracic air sac and clavicular air sac administration of isoflurane in sulphur-crested cockatoos (Cacatua galerita). J Avian Med Surg 15(3):170–177.
CASE 204 1 What possible differentials should be considered? There is marked thickening and scale encasing the rachis, with distortion of the inner groove. Differential diagnoses that should be considered include ectoparasites and bacterial and viral infections such as avian circoviruses. 2 What diagnostic tests should be performed to investigate the cause? A dissecting microscopic should be used to rule out ectoparasites and histopathologic examination of developing feather follicles can be performed. Laboratory investigation for avian circoviruses is also recommended and this case was positivefor avian circovirus by
Answers PCR using degenerate avian circovirus PCR primers. Awide range of bird species, including corvids, are susceptible to avian circovirus infection with increasing evidence indicating that broader host susceptibility should be considered for beak and feather disease virus (BFDV), since this infection has been detected in nonpsittacine birds including raptors. 3 What is the likely prognosis for birds with such lesions? Recent evidence suggests that BFDV, which is mainly a pathogen of psittacine birds, can also infect and cause transient disease in nonpsittacine birds with some recovering normal plumage. At least one molt should be permitted to assess the degree of damage to pterylae. Further reading Stewart ME, Perry R, Raidal SR (2006) Identification of a novel circovirus in Australian ravens (Corvus coronoides) with feather disease. Avian Pathol 35:(2):86–92.
CASE 205 1 What are your differential diagnoses for a distended coelomic cavity in a canary? Intestinal disease (coccidiosis, flagellates such as Cochlosoma spp., bacterial enteritis, sudden nutritional change); reproductive tract disease (egg binding, salpingitis/impacted oviduct, egg-related peritonitis, ovarian cysts); liver disease (atoxoplasmosis, yersiniosis, mycobacteriosis, chlamydiosis, neoplasia, noninfectious hepatitis or hepatic lipidosis); cardiac disease (congestive heart failure); neoplasia of any coelomic organs. 2 At what age are canaries most likely to be affected by intestinal coccidiosis, and why? Juvenile birds, because of their poorly developed immune system (no vertical transfer of coccidial immunity) and regular contact with the excretions of their subclinically (and hence oocyst shedding) infected parents. 3 What is the life cycle of intestinal coccidiosis (Ispora canaria) in canaries? Orally ingested oocysts excyst to form sporozoites within the intestinal tract. These sporozoites undergo several generations of asexual schizogony and produce merozoites. The sexual gametogony of these merozoites then produces oocysts, which are excreted in the feces. In intestinal coccidiosis all stages develop within the intestinal wall. Further reading Sandmeier P, Coutteel P (2006) Management of canaries, finches and mynahs. In: Clinical Avian Medicine, Vol. 2. (eds. GJ Harrison, TL Lightfoot) Spix Publishing, Palm Beach, pp. 901–903.
CASE 206 1 What are the differential diagnoses? What is the most likely diagnosis? Stress-induced hyperglycemia, hypoglycemia induced by weight reduction and re-entering flights at quarry, lead poisoning (due to risk of having been fed shot quarry), hypocalcemia (due to failure to feed or consume a whole carcase diet), West Nile virus infection, organophosphate poisoning (due to mobilization of organophosphates from fat stores during weight loss), hepatopathy, septicemia. For an accipiter with this presentation, specifically during training or retraining, the most likely cause is ‘stress-induced hyperglycemia’ (otherwise known as stressinduced diabetes). 2 What is your diagnostic plan? How would you treat this bird if you confirm your suspicion? A CBC and plasma biochemistry panel would be a first step. Normal blood glucose levels in a resting, trained, and unstressed northern goshawk are 18–22 mmol/L (324–396 mg/dL). If the blood level exceeds 23mmol/L (414mg/dL), then a subtle and abnormal startle response may be seen, with a high risk of a generalized tonic–clonic seizures when the blood glucose level is >27 mmol/L (>486 mg/dL). With blood levels between 23 and 27 mmol/L (414 and 486mg/dL), administration of midazolam or diazepam, together with a darkened, quiet, and calm environment, will typically allow clinical signs to resolve and normalize within 2–3 days. If blood glucose levels exceed 27 mmol/L (>486 mg/dL), once daily administration of 1–2 units of 24-hour insulin for 1–2 days is likely to be required in order to control seizures. 3 What action can be taken to avoid this situation? Accipiters are prone to stress, especially during initial training or retraining. In part this is caused by the enforced proximity to humans at that time, to whom they are unhabituated. Traditionally, these birds would have been placed on perches at ground level during this training. Such birds would naturally perch in the branches of trees, waiting to fly down into quarry. It is unnatural and stressful for them to be held at ground level. By placing the accipiter on a high perch (2–3 meters above ground level) so they can look down on their handlers and immediate environment during initial training, they can become habituated to close proximity to handlers from a safe position. When handling by the austringer (a goshawk falconer) is increased, it is not as stressful as it would otherwise have been, and hyperglycemia does not occur. Further reading Forbes NA (1995) Stress hyperglycaemia in Northern goshawks (Accipiter gentilis). In: Proceedings of European Association of Avian Veterinarians Conference, Jerusalem, pp. 127–131.
Answers CASE 207 1 Describe the abnormal radiographic findings. This laterolateral radiographic projection shows a large caudoventral coelomic homogeneous soft tissue mass in the region of the liver, displacing caudodorsally the contrast filled proventriculus and ventriculus and compressing the thoracic air sacs. 2 List the differential diagnoses for this radiographic finding. Hepatopathy including neoplastic, infectious (bacterial, viral, parasitic, fungal), or inflammatory etiologies. There is also the possibility of cardiomegaly. As no ventrodorsal view is provided, it is difficult to assess for air sac disease, but severe granulomatous disease cannot be excluded. 3 Based on the suspected concurrent papillomatous lesion, what is your top differential diagnosis? Cholangiocarcinoma of the liver. Gastrointestinal adenocarcinoma and intrahepatic cholangiocarcinoma can occur concurrently with internal papillomatosis in New World psittacine parrots, as the latter is now known to be caused by oncogenic herpesviruses. Further reading Gibbons PM, Busch MD, Tell LA et al. (2002) Internal papillomatosis with intrahepatic cholangiocarcinoma and gastrointestinal adenocarcinoma in a peach-fronted conure (Aratinga aurea). Avian Dis 46(4):1062–1066.
CASE 208 1 What are the goals of traumatic brain injury treatment? Traumatic brain injury medical treatment is aimed at preventing or reducing the effects of secondary brain injury through maintaining adequate cerebral perfusion pressure, preventing or decreasing cerebral edema, and controlling intracranial pressure. 2 How would you treat traumatic brain injury in this bird? The bird should be placed in a dark, quiet area with an environmental temperature of 73ºF (23ºC), not warmer as hyperthermia may contribute to greater post-traumatic brain damage. Elevation of the head (up to 30º) may decrease intracranial pressure by facilitating venous and cerebrospinal fluid drainage. Administration of oxygen in an oxygen cage is recommended for moderate to severe cases. Intravenous hypertonic saline (7–7.8% NaCl; 3 mL/kg over 15 minutes) followed by crystalloid fluids at 50% of the normal rate, can be used instead of mannitol in hypovolemic or euvolemic patients to decrease intracranial pressure. Hypertonic saline is contraindicated in hyponatremic patients. Slow administration over 15 minutes of mannitol (0.25–1mg/kg IV q4–6h as needed for up to three boluses) should be considered, together with crystalloid fluids at 50% of the normal rate. Mannitol is contraindicated in hypovolemic patients. Ifthere is an insufficient response to
the first dose of mannitol, an additional bolus can be given 40–60 minutes later. Corticosteroids are not recommended to treat traumatic brain injury. 3 How would you manage pain? Slow administration of opioid drugs (e.g. buprenorphine in raptors) is recommended to treat pain and avoid intracranial pressure elevation secondary to the sympathetic response pain, but caution is warranted for patients unable to adequately ventilate. The use of NSAIDs in cases of traumatic brain injury in birds is only recommended once the patient is stabilized. Further reading Sanchez-Migallon Guzman D (2016) Systemic diseases: disorders of the neurological system. In: Avian Medicine, 3rd edn. (ed. J Samour) Elsevier, St. Louis, pp. 421–433.
CASE 209 1 Which blood vessels are suitable for venipuncture? The three major blood vessels that can used for venipuncture are: (1) The right jugular vein, located under the right lateral cervical apteria. The left jugular vein can be used, but is smaller than the right. (2) Either of the basilic veins, located on the ventral aspect of the elbow joint. (3) Either of the medial metatarsal veins, located on the medial aspect of the podotheca (the scaled part of the leg, below the tibiotarsal–tarsometatarsal joint). This vein is aligned with the second digit, the medial forward directed toe. It is very shallow, but can often not be visualized because of the keratinized skin overlying it. 2 How much blood can be safely collected from this bird? 9.45 ml of blood. The circulating blood volume of parrots is approximately 10% of their body weight. The amount of blood that can be collected from a healthy bird is 10% of the circulating blood volume (i.e. 1% of the bird’s body weight). 3 How would you handle the blood sample after collection to maximize the quality of the laboratory results? Immediately after collection the blood sample should be processed as follows: (1) Fresh blood smears should be made. Erythrocytes, after prolonged mixing with an anticoagulant such as K2EDTA, will often be distorted and have other artifactual changes that can affect assessment of their morphology. For this reason, fresh blood smears are preferred to smears made in the laboratory. (2) Blood intended for biochemical analysis is usually placed in lithium heparin, unless requested otherwise by an external laboratory. The sample should be gently mixed to prevent hemolysis associated with rough handling. If testing is likely to be delayed by more than 2 hours, the sample should be centrifuged and the plasma decanted into another container without anticoagulant and submitted to the laboratory. This prevents artifactual errors associated with prolonged contact
Answers between erythrocytes and plasma. (3) Blood intended for hematologic analysis should be placed in K2EDTA. Although white cell counts are often inaccurate using automated cell counters (due to the nucleated erythrocytes in avian blood), other parameters such as hematocrit and some secondary indices (e.g. MCV) can be measured accurately. Further reading Doneley R (2011) Clinical techniques. In: Avian Medicine and Surgery in Practice. CRC Press, Boca Raton, pp. 55–68.
CASE 210 1 What is your primary differential? Xanthoma or xanthomatous inflammation. 2 What is a unique characteristic of this lesion? Xanthomas are masses consisting of multinucleated giant cells, macrophages, and cholesterol clefts, occurring most commonly at sites of previous trauma or hemorrhage. 3 What is the recommendation for treatment? Surgical excision (with care as this tissues tends to be highly vascular and tends not to heal well); the surgical site may also be prone to trauma. Dietary improvement is recommended. Further reading Souza MJ, Johnstone-Mclean NS, Ward D et al. (2009) Conjunctival xanthoma in a blue and gold macaw (Ara ararauna). Vet Ophthalmol 12(1):53–55.
CASE 211 1 What anatomic features must be considered for intubation (211)? The trachea bifurcates typically closer to the glottis in most penguin species, because they possess a septum, variable in length depending on the species, which divides the trachea into right and left channels. Use of a large size endotracheal tube may result in mucosal trauma. Penguins also possess a horn-like projection arising from the ventral wall of the glottal opening (i.e. in the proximal trachea [crista ventralis]), which may also interfere with intubation. Therefore, a smaller number 1 or 2 endotracheal tube should be used. 2 What methods should be considered to maintain body temperature? Cold climate species require the use of ice, ice packs, or other ways to control/prevent hyperthermia, especially during the initial phase of anesthesia. However, with prolonged procedures, penguins (like other bird species) need to be warmed to maintain body temperature. 3 Which body position is best suited for penguins under general anesthesia? Recent studies performed in Humboldt penguins (Spheniscus humboldti)
indicated that significant changes in lung density and air sac volume occur in penguins with respect to recumbent orientation while anesthetized. These changes may have significant physiologic consequences, especially for birds in dorsal recumbency. Therefore, positioning in dorsal recumbency during anesthesia may not be appropriate for penguins because of their unique body shape and anatomy. Ventral recumbency should be prioritized for this species, particularly for long procedures. Further reading Nevitt BN, Langan JN, Adkesson MJ (2014) Comparison of air sac volume, lung volume, and lung densities determined by use of computed tomography in conscious and anesthetized Humboldt penguins (Spheniscus humboldti) positioned in ventral, dorsal, and right lateral recumbency. Am J Vet Res 75(8):739–745.
CASE 212 1 How does the healing rate of avian bone differ from mammalian bone? Ingeneral, bird bones heal at a much faster rate than mammalian bones. A repaired simple, uncomplicated closed humeral fracture will heal in 3 weeks in an adult healthy bird compared with an average of 8 weeks in a mammal. 2 What is the relative healing rate of various long bones in birds? The average healing time for avian long bones varies by location. For simple, repaired, uncomplicated closed fractures the following times are common: • Humerus: 3 weeks. • Radius/ulna: 4 weeks. • Metacarpus: 5–6 weeks. • Femur: 3 weeks. • Tibiotarsus: 4 weeks • Metatarsus: 6+ weeks. 3 Do bird bones heal by periosteal or endosteal callus formation? While avian bones produce both periosteal and endosteal callus, the fixation methods most commonly used in birds, such as IM–ESF tie-in and ESF, result in periosteal callus formation that creates a bridging osteosynthesis. In contrast, plate fixation results in less callus formation and more endosteal healing. Further reading Redig PT, Ponder J (2016) Management of orthopedic issues in birds. In: Avian Medicine, 3rd edn. (ed. J Samour) Mosby, St. Louis, pp. 312–350.
Answers CASE 213 1 What is the most likely diagnosis of these lesions, and how could this diagnosis be confirmed? The most likely diagnosis is an Avipoxvirus infection. Confirmation of the diagnosis can be achieved by histologic evaluation of the nodules, which are characterized by a palisade-like arrangement of epithelial cords with large granular intracytoplasmic inclusion bodies (also known as Bollinger bodies). 2 What is the mode of transmission for this disease? Mosquitoes are the most common vectors for transmission of Avipoxvirus. Mosquitoes obtain the virus by feeding on an infected bird with the virus circulating in the bloodstream, after which they feed on a susceptible host, transferring virus infection to the new host. On occasions, if there are abrasions of the mucous membranes or skin, the virus may also be transmitted indirectly from contaminated surfaces (e.g. food or drinking bowls) or airborne particles. Following infection, a bird remains viremic for a long time (up to 1 year), thereby acting as a reservoir of infection. 3 What therapeutic and preventive measures can be taken? Include the prognosis in your answer. No specific treatment is available. The skin lesions are often selflimiting, although severe infections may result in immunosuppression. Systemic antibiotic treatment may then be indicated. When the lesions on the beak prevent eating, force feeding (by gavage or ingluviotomy tube) is necessary. If the pigeons are not force fed, it is likely they will die due to inanition. In pigeons, commercial vaccines are available to prevent infection. Action can be taken to reduce mosquito numbers in the vicinity of pigeons (e.g. treating surfaces or shade netting with safe insecticidal surface spray). Once an outbreak has commenced, great care must be taken in handling and medicating patients to avoid transferring infection from bird to bird on your hands or clothing. With supportive care (and potentially the use of antibiotics) the prognosis is fair. Further reading Cooper JE, Harrison GJ (1994) Dermatology. In: Avian Medicine, Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, pp. 607–639.
CASE 214 1 What is the most important role of the ceca? The precise role of ceca in digestion remains unclear but it appears that bacteria in the ceca further digest and partially ferment digested foods into usable biochemical compounds that are absorbed through the cecal walls. Ceca may also function to separate the nutrient-rich fluid in partially digested food from the fibrous portion, which is eventually eliminated. 2 Not all birds have functional ceca. Which group of birds lack a functional cecum? Ceca are poorly developed or nonexistent in most arboreal birds
(e.g. psittacines and pigeons), perhaps because of the unacceptable weight of the watery, partially digested food in the intestine and the large structures required to handle it. Indeed, well-developed cecal fermentation is restricted to grounddwelling as well as flightless birds (e.g. ratites) and is much more common in mammals than in birds.
CASE 215 1 What is the most probable diagnosis? What other clinical signs are often seen? Spiral bacterial infection (organisms are suspected to belong to the genus Helicobacter). Common clinical signs reported in cases of spiral bacterial infection include red clogged nares, sneezing, reddened and blunted choanal papillae, oropharyngeal hyperemia, conjunctivitis, sinusitis, and periorbital swelling. Infected birds may also show general signs of illness, including lethargy, anorexia, and weight loss. 2 What is the method of choice for antemortem diagnosis? The method of choice for antemortem diagnosis is cytologic examination of swabs from the choana and the oropharynx, as efforts to culture spiral bacteria from cockatiels have been unsuccessful. Bacteria can be identified on smears stained with Gram stain or Romanowsky stain. 3 What is the recommended treatment regimen? Spiral bacterial infections have been treated successfully using doxycycline orally (25 mg/kg q12h for 3 weeks) or via the drinking water using doxycycline hyclate (400 mg/L for 30 days). As oral medication requires twice daily capture over several weeks and as intake of medication via the drinking water may not be guaranteed in severely ill birds, injectable doxycycline is preferred. As vitamin A deficiency contributes to respiratory disease in birds, a diet change to a more balanced, commercially available pelleted diet after treatment may also be beneficial. Further reading Evans EE, Wade LL, Flammer K (2008) Administration of doxycycline in drinking water for treatment of spiral bacterial infection in cockatiels. J Am Vet Med Assoc 232(3):389–393.
CASE 216 1 Name at least four criteria that can be used to determine the gender of a pigeon. The gender of pigeons cannot always be morphologically distinguished with complete certainty, but body size (larger in male), shape of the head (plumper in male), cere and eye cere (larger in male), and differences in specific behavior (males ‘coo’ more, walk more upright, have more fluffed up feathers) can be used as indications of gender determination.
Answers 2 The genes for the color of hair in mammals and feathers in birds are in part localized on the sex chromosomes. What is the major difference between sex chromosomes in birds compared with mammals? In mammals the X chromosome is the sex chromosome that carries the genes, while the Y chromosome does not. Female mammals carry two X chromosomes, while males carry the XY chromosomes. In birds, females (hens) have a Z and a W chromosome, while the cocks have two Z chromosomes. The Z chromosomes carry the genes (similar to the X chromosomes in mammals). 3 What is the gender of this pigeon? Based on what criteria can 100% accuracy be given that this is actually the gender? This is a male pigeon (cock). This can be determined with 100% accuracy as this bird has the color characteristics of a heterozygote. The genes for the (ash) red and blue (wild type) color of pigeons are located on the sex chromosomes. Red is the dominant color over the wild type color in pigeons. In this red pigeon, in many of the covert feathers and in particular on the tail feathers. The fact that blue streaks are seen in this ash-red pigeon, indicates that it must be a heterozygote for the color and therefore has to be a male pigeon. Further reading Arif Mümtaz. Pigeon genetics. Web page: http://mumtazticloft.com/m_ash-red.asp
CASE 217 1 What is the most likely etiology of this abnormality? Lead toxicosis. Proventricular impactions are commonly reported in lead poisoned waterfowl, consisting of grass or other vegetation fibers, corn or other grains, sand, or a combination of these items. Occasionally, impactions can include portions of the caudal esophagus, and even the entire length of the esophagus in severe cases. Other gross lesions in lead poisoned waterfowl may include emaciation, green discolored liver, bile-stained ventricular lining, pale streaked myocardium, and often the presence of lead shot or sinkers (fishing weights) in the ventriculus. 2 What is the most appropriate tissue to submit to confirm your presumptive diagnosis? Liver is the best tissue to submit to confirm a diagnosis. Liver lead levels >6 ppm (wet weight) are diagnostic for acute toxic exposure. If antemortem sampling is possible, whole, EDTA or heparinized blood (check with the laboratory what their requirement is) may be used for lead analysis. Blood lead levels >0.97µmol/L (>20 µg/dL) indicate exposure, and clinical signs are generally present with levels >2.41 µmol/L (>50 µg/dL). 3 What are the most common environmental sources for this etiology in waterfowl? Spent lead shot from hunting activities over, or near, bodies of water, and discarded or lost lead fishing sinkers (weights) or fishing tackle, are the most
common sources of lead poisoning globally. It has been proposed that waterfowl inadvertently ingest lead shot or sinkers when they are foraging for food or ingesting grit (ingested to assist with ventricular grinding function). In the USA, lead shot was banned for use during waterfowl hunting in 1991. However, residual lead shot persists in lakes and wetlands for many years after the cessation of use and lead toxicosis continues to cause problems in waterfowl (and scavenging carnivorous birds) in many areas. In situations where a lake water level is reduced due to weather factors or extraction, high incidence of lead toxicity can occur in a flock previously unaffected, due to access to lead on the substrate that was previously beyond reach. Further reading Wobeser GA (1997) Lead and other metals. In: Diseases of Wild Waterfowl, 2nd edn. Plenum Press, New York, pp. 163–178.
CASE 218 1 What is the most likely diagnosis? How would you confirm the diagnosis? This is the classical appearance of a cloacal papillomatous lesion, most often found in New World psittacines such as Amazon parrots, macaws, and conures. Most lesions are confined to the oropharyngeal and cloacal mucosa, although lesions might, more rarely, be found along the gastrointestinal tract. Initial confirmation can be obtained by applying 5% acetic acid topically and assessing for blanching of the surface. Histopathology and PCR techniques should also be performed on a biopsy sample. These papillomatous lesions have been associated with infections with psittacid herpesvirus (genotypes 1, 2, and 3). Psittacid herpesviruses are a heterogeneous group of viruses, currently divided into four genotypes and four serotypes, which have also been associated with an acute fatal infection in parrots (Pacheco’s disease). However, some birds survive the acute manifestations of the disease and may become latently infected, while others appear to become latently infected following an inapparent infection. 2 What surgical treatment would you perform? Several techniques for surgical removal of these masses have been described including blade excision, application of caustic substances, radiosurgical excision, cryosurgical removal, and laser surgery. Some of these methods might result in ablation or excision of the mass, but recurrence is common. These surgical procedures are very painful and require appropriate administration of analgesics and systemic antibiotics during the postoperative period and until the wounds heal. 3 What are your recommendations to the owner? What is the long-term prognosis for this bird? The owner should not keep this bird as a breeder. Depending on the genotype of the viruses and the species involved, these viruses can disseminate
Answers through a collection. The prognosis for curing the problem is guarded to poor. While surgery could relieve some of the discomfort for some time, recurrence is common as is development of internal papillomatous lesions (e.g. oropharyngeal) or neoplasia (e.g. biliary and pancreatic adenocarcinoma), which is often fatal. Further reading Styles DK, Tomaszewski EK, Jaeger LA et al. (2004) Psittacid herpesviruses associated with mucosal papillomas in neotropical parrots. Virology 325(1):24–35.
CASE 219 1 What is the most likely underlying cause? Frounce caused by Trichomonas gallinae. Other differential diagnoses are: candidiasis, trauma, Capillaria spp. infestation with secondary bacterial infection, bacterial stomatitis (e.g. Pseudomonas spp.), oral neoplasia with secondary bacterial infection, and poxvirus infection with secondary bacterial infection. A diagnosis in this bird cannot be made without cytology and microbiology. To confirm the diagnosis the flagellate can be collected from the oropharynx or esophagus by advancing a slightly moistened (in warm saline) cotton tipped applicator into the esophagus and moving this up and down a couple of times. After removing the swab, it can be compressed so that some fluid is expelled onto a slide. The fluid on the slide should then be examined immediately so that the flagellate can be seen swimming (circling) in the wet sample. A magnification of 10 × 20 is usually sufficient to see the typical movement of the flagellates. Thirty minutes to 1 hour after collection of the sample, the parasites will be difficult to recognize, as by then they will have stopped moving. A wet mount sample stained with Giemsa will allow identification of trichomonads, even when movement has ceased. 2 What is the most likely source of infection? Pigeon or dove prey ingestion. 3 What is the recommended treatment? Nitroimidazole class drug. The preferred drug is carnidazole (20–50 mg/kg one-off dose) or ronidazole (6–10 mg/kg PO q24h for 7 days). Metronidazole (50 mg/kg PO q24h for 5 days) may be used as well, but is considered less effective for the treatment of trichomoniasis. In any bird with severe oropharyngeal, esophageal, or crop (owls do not have one) disease, especially when they are already thin, supplementary feeding by gavage is essential. If gavage is challenging or stressful for the patient, an indwelling proventriculotomy tube, placed via the upper esophagus, is a good option. Further reading Greiner EC, Ritchie BW (1994) Parasites. In: Avian Medicine: Principles and Application. (eds. BW Ritchie, GJ Harrison, LR Harrison) Wingers Publishing, Lake Worth, p. 1013.
CASE 220 1 What pectoral limb fractures can be adequately stabilized with a wing wrap, and when should a body wrap be incorporated into the wrap? A figure-of-eight wrap provides adequate support for fractures involving the antebrachium, carpometacarpus, and digits. Wing wraps can be effective for some fractures of the pectoral girdle and humerus when used in conjunction with a body wrap or ‘belly band’. 2 Depending on patient size, what bandaging options can be considered for fractures of the tibiotarsus? A tape splint can be used to stabilize tibiotarsal fractures in small patients weighing