NAVLE Avian and Exotic Animal Medicine 5

Question 1

A 4-year-old African grey parrot presents with progressive ataxia, regurgitation, and a dilated proventriculus on radiograph. Crop biopsy reveals lymphoplasmacytic infiltration of the myenteric ganglia. Which of the following is the MOST accurate statement regarding the etiologic agent?

Accepted Answer

It is a negative-sense, single-stranded RNA virus in the family Bornaviridae that targets glial cells and neurons of the enteric and central nervous systems

Answer

Proventricular Dilatation Disease (PDD) is caused by Avian Bornavirus (ABV), a non-segmented, negative-sense, single-stranded RNA virus in the family Bornaviridae. It targets neurons and glial cells of both the enteric (myenteric plexus) and central nervous systems, producing lymphoplasmacytic ganglioneuritis. The other options describe incorrect viral families or pathomechanisms.

Question 2

A green iguana is presented for severe metabolic bone disease refractory to standard calcium and UVB supplementation. Bloodwork shows hypocalcemia, hyperphosphatemia, and markedly elevated PTH. Renal function tests reveal azotemia. Which pathophysiologic mechanism BEST explains this presentation?

Accepted Answer

Renal secondary hyperparathyroidism caused by impaired 1-alpha-hydroxylation of 25-hydroxyvitamin D3 and phosphate retention

Answer

This iguana has renal secondary hyperparathyroidism. Azotemia indicates renal disease, which impairs 1-alpha-hydroxylation of 25-hydroxyvitamin D3 in the kidneys, reducing calcitriol production. Reduced calcitriol impairs intestinal calcium absorption, and phosphate retention by the failing kidneys further drives hypocalcemia. The resulting PTH elevation mobilizes bone, leading to metabolic bone disease. This is distinct from nutritional secondary hyperparathyroidism, which occurs without azotemia.

Question 3

During anesthesia of a ball python for surgical removal of a retained spectacle, the veterinarian notes apnea persisting more than 10 minutes after isoflurane is discontinued. Which of the following BEST explains why reptiles are particularly susceptible to prolonged post-anesthetic apnea compared to mammals?

Accepted Answer

Reptiles rely primarily on peripheral chemoreceptors sensitive to PO2 rather than central CO2/pH-driven ventilatory drive, making hypercapnia a poor respiratory stimulus

Answer

Reptiles have a blunted central chemoreceptor response to hypercapnia compared to mammals. Their ventilatory drive depends more on peripheral oxygen sensing, and they tolerate wide swings in PCO2 with minimal respiratory response. This means rising CO2 after anesthesia does not reliably stimulate breathing, causing prolonged apnea. The cardiac shunt (option D) contributes to anesthetic uptake/elimination differences but is not the primary reason for post-anesthetic apnea.

Question 4

A ferret presents with episodic weakness, ptyalism, pawing at the mouth, and hypoglycemia (BG 42 mg/dL) that resolves with dextrose. Abdominal ultrasound reveals a 1.2 cm hypoechoic pancreatic nodule. Intraoperative exploration reveals a solitary mass in the left limb of the pancreas with no visible metastasis. Which of the following perioperative management strategies carries the GREATEST risk of iatrogenic harm in this patient?

Accepted Answer

Administering a bolus of 50% dextrose IV immediately before mass removal

Answer

Administering a concentrated dextrose bolus (50%) before or during insulinoma surgery is dangerous because it acutely stimulates the tumor to release a massive surge of insulin, potentially precipitating severe rebound hypoglycemia during or immediately after surgery. The correct approach is to maintain euglycemia with a dilute dextrose CRI (e.g., 2.5%) rather than bolus high-concentration dextrose. The fracture-crush technique is an accepted method for ferret pancreatectomy, and frequent glucose monitoring is appropriate and safe.

Question 5

A 6-year-old bearded dragon (Pogona vitticeps) presents with bilateral periocular swelling, lethargy, and anorexia. Cytology of aspirated periocular material reveals caseous debris with heterophils. Culture yields Salmonella arizonae. Which of the following statements about treatment is MOST accurate?

Accepted Answer

Surgical debridement of caseous exudate combined with systemic antimicrobials is required, as reptilian heterophilic pus does not liquefy and will not resolve with antibiotics alone

Answer

Reptiles lack the enzymatic machinery to liquefy caseous (inspissated) pus as mammals do — their heterophils do not produce the proteases needed for liquefaction. Consequently, antibiotic therapy alone cannot eliminate the solid caseous mass; surgical debridement or curettage is mandatory to remove the inspissated material, followed by systemic antimicrobials based on culture and sensitivity. Enrofloxacin is routinely used in bearded dragons and is not contraindicated; cartilage concerns apply more to immature large-breed dogs.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Avian and Exotic Animal Medicine 5