BCSE Large Animal Internal Medicine 5 — Questions and Answers
Question 1: A heavily pregnant cow is found in lateral recumbency and unable to rise. She is alert but unable to stand despite calcium treatment. Her selenium and vitamin E levels are low. What condition should be considered?
- White muscle disease (nutritional myodegeneration) (Correct answer)
- Downer cow syndrome with sciatic nerve damage
- Grass tetany (hypomagnesemia)
- Transit tetany (transport hypocalcemia)
Correct answer: White muscle disease (nutritional myodegeneration)
White muscle disease from selenium/vitamin E deficiency causes myodegeneration that may present as recumbency in adult cattle; treatment with selenium and vitamin E supplementation is indicated.
Question 2: Equine infectious anemia (EIA) is diagnosed using which regulatory test in the United States?
- Virus neutralization test
- Coggins test (agar gel immunodiffusion) (Correct answer)
- ELISA for viral capsid antigen
- PCR for EIA proviral DNA
Correct answer: Coggins test (agar gel immunodiffusion)
The Coggins test (agar gel immunodiffusion for antibodies to EIA p26 antigen) is the official USDA-recognized test for regulatory purposes including interstate movement.
Question 3: A goat herd experiences multiple abortions in the last trimester. Placental lesions show thickened, leathery cotyledons with tan exudate. Zoonotic risk is high. Which pathogen is most likely?
- Listeria monocytogenes
- Toxoplasma gondii
- Coxiella burnetii (Q fever) (Correct answer)
- Chlamydophila abortus (Enzootic abortion)
Correct answer: Coxiella burnetii (Q fever)
Coxiella burnetii causes abortion with characteristic placentitis and poses significant zoonotic risk to farm workers, veterinarians, and pregnant women through inhalation of contaminated aerosols.
Question 4: In horses with large colon volvulus (LCV), which intraoperative finding is the most reliable predictor of a poor prognosis requiring resection or euthanasia?
- Duration of colic greater than 6 hours
- Failure of colon to reperfuse with pink color and motility after detorsion (Correct answer)
- Presence of free peritoneal fluid on abdominocentesis
- Heart rate greater than 80 bpm preoperatively
Correct answer: Failure of colon to reperfuse with pink color and motility after detorsion
Failure of the large colon to regain normal pink color, palpable arterial pulse, and motility within minutes of detorsion indicates irreversible ischemia and necessitates resection or euthanasia.
Question 5: A beef cow herd experiences multiple sudden deaths in young calves with no premonitory signs. Post-mortem reveals bloody pericardial effusion and a spleen with a 'ground glass' appearance. Which pathogen is responsible?
- Clostridium chauvoei (blackleg)
- Bacillus anthracis (anthrax) (Correct answer)
- Clostridium haemolyticum (bacillary hemoglobinuria)
- Pasteurella multocida septicemia
Correct answer: Bacillus anthracis (anthrax)
Anthrax causes sudden death with bloody orifice discharge, bloody pericardial effusion, and characteristic splenomegaly with a friable, 'ground glass' spleen; it is a reportable foreign animal disease.
Question 6: Which physiologic mechanism best explains the development of hypocalcemia in dairy cows fed high-cation-anion difference (DCAD) diets in late gestation?
- High potassium suppresses PTH secretion directly
- Metabolic alkalosis reduces tissue sensitivity to PTH and decreases intestinal calcium absorption (Correct answer)
- High sodium competitively inhibits calcium reabsorption in the kidney
- Dietary calcium binds to excess potassium forming insoluble complexes
Correct answer: Metabolic alkalosis reduces tissue sensitivity to PTH and decreases intestinal calcium absorption
Dietary-induced metabolic alkalosis decreases PTH receptor sensitivity and reduces 1,25-dihydroxyvitamin D production, impairing intestinal calcium absorption and bone calcium mobilization.
Question 7: A 5-year-old alpaca presents with neurologic signs including head tilt, nystagmus, and circling to the right. CSF analysis shows eosinophilic pleocytosis. What is the most likely diagnosis?
- Listeria monocytogenes encephalitis
- Parelaphostrongylus tenuis (meningeal worm) infection (Correct answer)
- Polioencephalomalacia (thiamine deficiency)
- Bovine herpesvirus-5 encephalitis
Correct answer: Parelaphostrongylus tenuis (meningeal worm) infection
Parelaphostrongylus tenuis (meningeal worm) causes eosinophilic meningitis and progressive neurologic signs in aberrant camelid hosts, with eosinophilic CSF pleocytosis being a characteristic finding.
BCSE Large Animal Internal Medicine 5
A heavily pregnant cow is found in lateral recumbency and unable to rise.
She is alert but unable to stand despite calcium treatment.
Her selenium and vitamin E levels are low.
What condition should be considered?