BCSE Large Animal Internal Medicine 2 — Questions and Answers
Question 1: A 6-year-old quarter horse presents with acute onset of moderate colic. On rectal palpation, you feel a tightly distended loop of small intestine in the right dorsal quadrant. Which diagnosis is most consistent with these findings?
- Right dorsal displacement of the large colon
- Ileal impaction (Correct answer)
- Duodenal ulceration
- Gastric dilation
Correct answer: Ileal impaction
Ileal impaction presents with moderate to severe colic and a palpable, firm, distended loop of small intestine on rectal examination, typically in the right dorsal abdomen.
Question 2: Which of the following electrolyte abnormalities is most commonly associated with grain overload (carbohydrate engorgement) in cattle?
- Hypernatremia
- Hypocalcemia
- Metabolic acidosis with D-lactatemia (Correct answer)
- Hyperkalemia
Correct answer: Metabolic acidosis with D-lactatemia
Grain overload causes rapid fermentation producing D-lactic acid, leading to metabolic acidosis and D-lactatemia, which can be severe and life-threatening.
Question 3: A 4-year-old thoroughbred racehorse presents with exercise intolerance and a grade 4/6 holosystolic murmur loudest at the left cardiac apex. What is the most likely diagnosis?
- Aortic regurgitation
- Tricuspid regurgitation
- Mitral regurgitation (Correct answer)
- Ventricular septal defect
Correct answer: Mitral regurgitation
Mitral regurgitation produces a holosystolic murmur heard loudest at the left cardiac apex (mitral valve area) in horses.
Question 4: Hypocalcemia in periparturient dairy cows (milk fever) most commonly occurs due to which pathophysiologic mechanism?
- Inadequate dietary calcium intake during the dry period
- Failure to mobilize bone calcium and inadequate intestinal calcium absorption at calving (Correct answer)
- Excessive renal calcium excretion triggered by parturition hormones
- Sequestration of calcium by the uterus during calving
Correct answer: Failure to mobilize bone calcium and inadequate intestinal calcium absorption at calving
Milk fever results from the sudden high calcium demand of colostrum production overwhelming the cow's ability to mobilize skeletal calcium and upregulate intestinal absorption.
Question 5: A horse with confirmed equine protozoal myeloencephalitis (EPM) caused by Sarcocystis neurona is started on treatment. Which drug combination is FDA-approved specifically for EPM treatment in horses?
- Metronidazole and rifampin
- Ponazuril or diclazuril monotherapy
- Pyrimethamine and sulfadiazine
- Both B and C are approved options (Correct answer)
Correct answer: Both B and C are approved options
Ponazuril (Marquis), diclazuril (Protazil), and the combination of pyrimethamine/sulfadiazine (Re-Balance) are all FDA-approved treatments for EPM in horses.
Question 6: In cattle with bovine respiratory disease (BRD), which pathogen is most commonly implicated as the primary viral initiator that predisposes animals to secondary bacterial pneumonia?
- Bovine respiratory syncytial virus (BRSV)
- Bovine viral diarrhea virus (BVDV) (Correct answer)
- Infectious bovine rhinotracheitis virus (IBR/BHV-1)
- Bovine parainfluenza-3 virus (PI-3)
Correct answer: Bovine viral diarrhea virus (BVDV)
BVDV causes immunosuppression by infecting and depleting lymphocytes, dramatically increasing susceptibility to secondary bacterial pathogens in the BRD complex.
Question 7: A llama presents with progressive weight loss, bottle jaw (submandibular edema), and pale mucous membranes. Fecal flotation reveals numerous strongyle-type eggs. What is the most likely primary pathogen?
- Haemonchus contortus (Correct answer)
- Ostertagia ostertagi
- Trichostrongylus colubriformis
- Cooperia oncophora
Correct answer: Haemonchus contortus
Haemonchus contortus is a blood-sucking abomasal parasite causing severe hypoproteinemia, bottle jaw, anemia, and weight loss in camelids and small ruminants.
BCSE Large Animal Internal Medicine 2
A 6-year-old quarter horse presents with acute onset of moderate colic.
On rectal palpation, you feel a tightly distended loop of small intestine in the right dorsal quadrant.
Which diagnosis is most consistent with these findings?