Avian Medicine and Surgery

Self-Assessment Color Review, Second Edition

Neil A. Forbes, David Sanchez-Migallon Guzman, Neil A. Forbes, David Sanchez-Migallon Guzman

• Publisher: CRC Press
• Year: 2017
• eBook ISBN: 9781351645683
• Edition: 2
• Topic: Medizin
• Subtopic: Veterinärmedizin

This completely revamped second edition of Avian Medicine and Surgery includes over 260 all-new colour illustrated cases, with questions and answers fully exploring a breadth of diseases and disorders. Avian patients are a routine part of the veterinary case load and are being seen by many clinicians across the world. This book provides a unique quick reference for clinicians and a useful self-test for students by offering comprehensive, clinically-oriented information that can be quickly accessed, easily understood and applied.

With contributions from leading international authorities with diverse fields of expertise, the book covers a wide range of disciplines, organ systems and species. The cases are presented in a random order, just as they would appear in daily practice, challenging the reader to address real clinical situation and offering, where possible, a comprehensive solution.

Answers

CASE 1

1 What are the main differential diagnoses? Differential diagnoses to be taken into consideration are: iron storage disease (ISD), bacterial hepatitis, diffuse fatty liver (hepatic lipidosis).

2 What complementary test would you request or perform? Liver biopsy would be the best way to confirm ISD. A complete blood panel would help to determine if the condition has an infectious origin. In this case, fine needle aspiration was performed and the presence of hemosiderin aspirate was suggestive of ISD.

3 How would you treat this condition? While this condition can be controlled by a low iron diet, the use of tannins and other oral compounds will not decrease the iron liver content once iron is already stored there; on the other hand, cycles of phlebotomies (2 mL of blood/kg once a week), coupled with the use of iron chelating agents, such as deferoxamine (100 mg/kg SC q24h) and deferiprone, has been described and looks a viable option. The latter act by binding free iron in the bloodstream and enhancing its elimination in the urine. Even if ISD can be treated, or at least controlled, both the cost of the treatment and the commitment asked of the owner are considerable.

Further reading

Cornelissen H, Ducatelle R, Roels S (1995) Successful treatment of a channel-billed toucan (Ramphastos vitellinus) with iron storage disease by chelation therapy: sequential monitoring of the iron content of the liver during the treatment period by quantitative chemical and image analyses. J Avian Med Surg 9(2):131–137.

CASE 2

1 What advice could you give to improve the reproductive success in this collection? Flamingos are colony breeders. A large group is needed to trigger breeding behavior. The zoo can try to acquire more individuals. Several artificial devices have been used successfully to mimic a larger flock: placing mirrors, loudspeakers with flock noise, placing artificial nests. Rainfall is also a powerful trigger. Nests are fashioned from mounds of soil. These should be removed after one breeding season and fresh mounds supplied at the start of the next, which also forms a trigger for nest building and breeding. Misting the area regularly may also be useful. Particular care must also be taken to select animals from the same species, since hybridization is common between flamingo species, the offspring being infertile.

2 List some possible causes of low egg fertility in flamingo flocks? What management techniques can be used to overcome this difficulty? Egg fertility in captive flamingo flocks is often low (30%). Several causes have been implicated. Flamingos in captive collections tend to be pinioned. Pinioning is believed to introduce additional physical difficulties for successful copulation in long legged and long winged species such as flamingos. While one option is to maintain fully flighted birds in large netted enclosures, such species are prone to flight injuries against the netting, so these enclosures are not ideal. Flamingos cannot be kept fully winged, unless enclosed. Viable chick numbers per breeding pair have been normalized by candling eggs at 10 days of incubation and removing all clear eggs. If an egg is removed at 10 days, the hen will recycle, giving the pair an additional chance to produce a viable fertile egg. The removal of clear eggs is carried out only on the first two cycles.

3 What management actions can be taken to reduce hand-reared chick mortality during the first days of life? Captive reared flamingo chicks are intensely aggressive towards each other immediately after hatching. Chicks should be kept individually in nest bowls until 5 days of age. At this time they may be mixed as a group of three (not two), in which situation aggression between chicks does not occur. Flamingo chicks are naturally long boned and fast growing. When hand-rearing chicks, a significant percentage seem to have a compulsive behavior to eat parts of the egg shell soon after hatching. When such ingestion occurs, a significant mortality level will occur, due to small intestine perforation caused by trauma from sharp edges of their own ingested egg shells.

Further reading

Batty M, Jarrett NS, Forbes N et al. (2006) Hand-rearing Greater Flamingos Phoenicopterus ruber roseus for translocation from WWT Slimbridge to Auckland Zoo. Int Zoo Year Book 40(1):261–270.

Wyss FS, Wenker C (2015) Phoenicopteriformes. In: Fowler’s Zoo and Wild Animal Medicine, Vol. 8, 1st edn. (eds. RE Miller, ME Fowler) Elsevier, St. Louis, pp. 105–112.

CASE 3

1 What is your problem list, differential diagnosis, and most likely diagnosis? The problem list should include: malnutrition, intermittent vomiting, feather damaging behavior, obesity, possible ileus, coelomic pain, leukocytosis, hyperamylasemia, and hypercholesterolemia. The differential diagnoses could include the following: enteritis, hepatopathy, pancreatic disease, gastrointestinal foreign body, and neoplasia of coelomic organs. The most likely diagnosis, based on the hyperamylasemia, is pancreatic disease. This can be associated with toxins (zinc, mycotoxins), high fat diets and obesity, neoplasia, trauma, or infection (bacterial, viral, or chlamydial). Pancreatitis develops when there is activation of the digestive enzymes (trypsin, protease, and phospholipase amongst others) within the gland, with resultant pancreatic autodigestion.

2 What further diagnostics could be used to confirm your tentative diagnosis? Further diagnostic testing could include: (1) Radiographs. To assess for the presence of hepatomegaly, ileus, and, with contrast, gastrointestinal foreign bodies. Coelomic fat, effusions, or organomegaly can lead to reduced serosal detail, limiting the usefulness of this modality. (2) Ultrasound. To differentiate between fluid and soft tissue opacities and identify specific organs. (3) Endoscopy and biopsy. The pancreas is best evaluated via the right coelomic approach (e.g. caudal thoracic or abdominal air sac). (4) Coeliotomy and biopsy. The pancreas is readily accessible via a ventral midline approach.

3 How would you treat this patient? There is little evidence-based information on the treatment of pancreatitis in birds, and most treatment regimens are extrapolated from small animal medicine. They revolve around:

• Reducing the workload on the pancreas:

◦ Conversion to a low-fat balanced diet (e.g. formulated diet and vegetables) reduces the amount of fat presented for digestion, and reduces the pancreatic workload.

◦ Increasing the amount of exercise (e.g. through the introduction of foraging activities) will improve tissue perfusion, especially of the pancreas.

◦ Supplementing the diet with pancreatic enzyme extracts is reported in people.

◦ There is no indication for fasting a bird with pancreatitis; indeed, such an approach may well precipitate a hypoglycemic crisis, collapse, and even death.

• Analgesia. Pancreatic disease can be painful. NSAIDs (e.g. meloxicam) are usually avoided where there is potential gastrointestinal dysfunction, leaving opioids as the mainstay of therapy. As opioids may potentially exacerbate ileus, synthetic opioids such as tramadol may be a suitable choice.

• Anti-inflammatory therapy. In recent years omega 3 and 6 essential fatty acids have been used for their anti-inflammatory, lipid stabilizing, antineoplastic and other potential qualities.

Birds that survive a bout of acute pancreatitis should be regularly monitored for evidence of pancreatic insufficiency and diabetes mellitus, both well-recognized sequelae to acute pancreatitis in mammals. Regular weight checks and annual blood screening may detect complications before they become life threatening. Most pancreatic disease is diagnosed as end-stage pancreatic atrophy, usually found at necropsy. There is obviously scope for earlier intervention in these cases.

Further reading

Candeletta SC, Homer BL, Garner MM et al. (1993) Diabetes mellitus associated with chronic lymphocytic pancreatitis in an African grey parrot (Psittacus erithacus erithacus). J Assoc Avian Vet 7:39–43.

Doneley R (2001) Acute pancreatitis in parrots. Aust Vet J 79:409–411.

Phalen DN, Falcon M, Tomaszewski EK (2007) Endocrine pancreatic insufficiency secondary to chronic herpesvirus pancreatitis in a cockatiel (Nymphicus hollandicus). J Avian Med Surg 21(2):140–145.

Schmidt RE, Reavill DR (2014) Lesions of the avian pancreas. Vet Clin North Am Exot Anim Pract 17:1–11.

CASE 4

1 How should one interpret the complete blood cell count? The bird has a pancytopenia based on the low total leukocyte count and the severe anemia (in general the normal PCV of birds ranges between 35 and 55%). The refractometric total protein suggests a hyperproteinemia (in general the normal refractometric total protein of birds ranges between 35 and 55 g/L [3.5 and 5.5g/dL]); however, this was not indicated by the total protein value from the plasma biochemistry profile.

2 How should one interpret the image of the blood film (4)? The heterophil exhibits 3+ toxicity. The erythrocytes reveal hypochromasia.

3 What is the significance of the cells in the image of the blood film? The toxic (3+) heterophil is indicative of a severe inflammatory leukogram regardless of the actual total leukocyte count. The erythrocytes lack polychromasia, indicating a nonregenerative response to the anemia. The presence of hypochromatic erythrocytes is indicative of iron deficiency, which likely is associated with chronic inflammatory disease; however, nutritional deficiency leading to iron deficiency or chronic lead toxicosis should also be considered.

Further reading

Campbell TW (2015) Peripheral bood of birds. In: Exotic Animal Hematology and Cytology, 4th edn. Wiley Blackwell, Ames, pp. 37–66.

CASE 5

1 Describe suitable endoscopy instrumentation required for the following procedures:

• Coelioscopy with kidney and liver biopsies in a 1 kg raptor. The 2.7 mm, 30° telescope, housed within a 4.8 mm operating sheath to allow introduction of flexible instruments, is ideal and is the most popular system amongst avian and exotics veterinarians. 5-Fr biopsy forceps are used to obtain the kidney biopsy. Ideally, 5-Fr single-action scissors are required to first incise the air sac and hepatoperitoneal membrane prior to obtaining a liver biopsy using 5-Fr biopsy forceps.

• Tracheoscopy in a 400 gram parrot. Ideally, a 1.9 mm telescope with an integrated sheath would be used. In birds with smaller tracheas, a 1-mm semi-rigid endoscope is often required. However, in a medium sized parrot, it is often possible to use the 2.7 mm telescope without a protective sheath to reduce the diameter. The trachea acts as a biological sheath such that instruments can be passed down the trachea alongside the telescope.

• Air sac tube placement in a 400 gram parrot. Any endoscope 1–3 mm in diameter (including the 2.7 mm telescope without a protective sheath) can be used. The endotracheal tube is placed over the endoscope and once the endoscope is appropriately positioned within the caudal thoracic air sac, the endotracheal tube can be pushed off the telescope and into the air sac. The size of the air sac tube should be comparable to the tracheal diameter, and for a 400 gram parrot, 4–5 mm would be appropriate.

• Cloacoscopy in a 3 kg goose. A 2.7 mm, 30° telescope, housed within a 4.8 mm operating sheath, is most popular, but other sizes may be suitable as long as ports are available for saline irrigation. Warm (39–41°C [103–105°F]) saline infusion is required for visualization, connected to the ingress port of the operating sheath.

2 Contrary to reptile and mammal coelioscopy/laparoscopy, why is CO₂ insufflation contraindicated and not required for avian coelioscopy? CO₂ insufflation is not required in avian coelioscopy as the endoscope is inserted into and operated within the air sac system, which provides a working space that is not present in other taxa. CO₂ insufflation is contraindicated as CO₂ inhalation results in immediate death, and is a recognized method of euthanasia in birds.

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? As the endoscope is operated within the air sac system, any air movement between the endoscope and the body wall, or through the operating sheath system, is tantamount to breat...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Preface
• Contributors
• Dedications
• Acknowledgments
• Photo Credits
• Abbreviations
• Broad Classification of Cases
• Questions
• Answers
• Index
• Also available in the self-assessment color review series