BCSE Large Animal Internal Medicine 3 — Questions and Answers
Question 1: A 3-week-old calf presents with profuse watery diarrhea, severe dehydration, and weak suckle reflex. Blood gas shows pH 7.08, bicarbonate 8 mEq/L, and strong ion gap elevation. Which pathogen is most consistent with this clinical picture in calves of this age?
- Bovine rotavirus
- Cryptosporidium parvum (Correct answer)
- Escherichia coli K99 (F5)
- Salmonella typhimurium
Correct answer: Cryptosporidium parvum
Cryptosporidium parvum is the predominant cause of profuse, watery scours in calves aged 5–21 days with severe metabolic acidosis due to D-lactic acid production.
Question 2: Which clinical sign is pathognomonic for tetanus in horses?
- Trismus (lockjaw) with erect ears and tail elevation (Correct answer)
- Flaccid paralysis of the hindlimbs
- Intermittent opisthotonus without muscle rigidity
- Hypersalivation with dysphagia only
Correct answer: Trismus (lockjaw) with erect ears and tail elevation
The combination of trismus, risus sardonicus (facial muscle contraction), erect ears, tail elevation, and generalized extensor rigidity triggered by stimuli is pathognomonic for tetanus.
Question 3: Left displacement of the abomasum (LDA) in dairy cows most commonly occurs in which time period relative to calving?
- Last 2 weeks of gestation
- First 6 weeks postpartum (Correct answer)
- 3–6 months postpartum
- Mid-lactation (6–9 months)
Correct answer: First 6 weeks postpartum
LDA occurs most commonly in the first 6 weeks after calving when the rumen contracts post-partum, leaving space for the gas-filled abomasum to displace leftward.
Question 4: A 10-year-old mare in the third trimester of pregnancy presents with sudden onset of severe weakness, recumbency, and muscle trembling. Serum chemistry shows calcium 5.8 mg/dL. Which treatment should be administered immediately?
- IV glucose (50% dextrose)
- Oral calcium propionate gel
- Slow IV calcium borogluconate (Correct answer)
- IM magnesium sulfate
Correct answer: Slow IV calcium borogluconate
Hypocalcemia in late-gestation mares is treated with slow IV administration of calcium borogluconate while monitoring heart rate to avoid cardiac arrhythmias.
Question 5: Equine recurrent uveitis (ERU) is most strongly associated with infection by which pathogen in endemic areas of the US?
- Equine herpesvirus-1
- Leptospira spp. (Correct answer)
- Streptococcus equi subsp. equi
- Borrelia burgdorferi
Correct answer: Leptospira spp.
Leptospiral infection is the most common identifiable cause of ERU, with Leptospira antibodies and organisms frequently found in vitreous humor of affected horses.
Question 6: In sheep with polioencephalomalacia (PEM), which vitamin deficiency is the underlying cause?
- Vitamin A
- Vitamin D
- Thiamine (Vitamin B1) (Correct answer)
- Cobalamin (Vitamin B12)
Correct answer: Thiamine (Vitamin B1)
PEM in ruminants results from thiamine (B1) deficiency, which disrupts neuronal energy metabolism, leading to cerebrocortical necrosis.
Question 7: Which finding on thoracic ultrasound is most indicative of fibrinous pleuropneumonia in a horse?
- Hyperechoic lung surface with comet-tail artifacts
- Anechoic fluid with fibrin strands and consolidated lung lobes (Correct answer)
- Diffuse hyperechoic pleural thickening without fluid
- Small volume of anechoic pleural fluid only
Correct answer: Anechoic fluid with fibrin strands and consolidated lung lobes
Fibrinous pleuropneumonia characteristically produces hypoechoic to anechoic pleural fluid with echogenic fibrin strands and ventrally consolidated lung visible on ultrasound.
BCSE Large Animal Internal Medicine 3
A 3-week-old calf presents with profuse watery diarrhea, severe dehydration, and weak suckle reflex.
Blood gas shows pH 7.08, bicarbonate 8 mEq/L, and strong ion gap elevation.
Which pathogen is most consistent with this clinical picture in calves of this age?