NAVLE Small Ruminant Medicine (Sheep and Goats)

Question 1

A 3-year-old dairy goat presents with progressive weight loss, decreased milk production, and bilateral carpal swelling. Lung auscultation reveals diffuse crackles. Cerebrospinal fluid analysis shows mononuclear pleocytosis. The most likely diagnosis is:

Accepted Answer

Caprine Arthritis Encephalitis (CAE) virus infection

Answer

CAE virus (a lentivirus) in adult goats classically presents as chronic progressive polyarthritis (especially carpal joints) combined with interstitial pneumonia and occasional leukoencephalomyelitis. Maedi-Visna is the sheep equivalent but does not cause arthritis as prominently. Caseous lymphadenitis causes abscessation, not arthritis + pneumonia. Mycoplasma causes acute febrile arthritis.

Question 2

A flock of sheep presents with sudden deaths in 2-to-6-week-old lambs that were thriving until 24 hours prior. Necropsy reveals hemorrhagic abomasal and intestinal lesions with gas in the intestinal lumen. Gram-positive rods are cultured. The most appropriate preventive strategy for next year's lamb crop is:

Accepted Answer

Vaccinate ewes with Clostridium perfringens types C and D toxoid 4–6 weeks before lambing

Answer

Overeating disease (pulpy kidney) caused by Clostridium perfringens type D and enterotoxemia type C are the primary clostridial diseases of young lambs. Vaccinating ewes 4–6 weeks pre-lambing ensures high colostral antibody titers that passively protect newborn lambs. Antibiotic prophylaxis at birth is not practical or regulatory-appropriate for herd prevention.

Question 3

A 2-year-old sheep presents with acute blindness, head pressing, and opisthotonus. The animal has been on a high-grain diet with limited forage. Blood thiamine levels are low. Which treatment should be administered immediately?

Accepted Answer

Thiamine (vitamin B1) 10–20 mg/kg IV or IM

Answer

Polioencephalomalacia (PEM) in sheep is caused by thiamine deficiency, often triggered by high-grain diets that favor thiaminase-producing rumen bacteria. Clinical signs include blindness, cortical signs, and opisthotonus. Immediate high-dose thiamine (B1) administration is the treatment of choice. Dextrose worsens thiamine deficiency; dexamethasone is adjunctive at best.

Question 4

Ovine Progressive Pneumonia (OPP) caused by Maedi-Visna virus is best controlled in a flock through which strategy?

Accepted Answer

Test-and-cull seropositive animals combined with separating lambs from seropositive ewes at birth

Answer

Maedi-Visna/OPP is a lentiviral infection with no vaccine or cure. Control relies on identifying seropositive animals via AGID or ELISA and removing them, combined with preventing transmission to lambs via infected colostrum/milk by separating and heat-treating or discarding colostrum. There is no arthropod vector; it is spread by close contact and milk.

Question 5

A goat herd experiences multiple does with profuse watery diarrhea, weight loss, and bottle jaw (submandibular edema) over several months. Fecal egg counts reveal heavy Haemonchus contortus burdens. Which anthelmintic resistance testing method is most appropriate to guide drug selection?

Accepted Answer

Fecal Egg Count Reduction Test (FECRT) comparing pre- and post-treatment counts

Answer

The Fecal Egg Count Reduction Test (FECRT) is the gold-standard field test for anthelmintic resistance. Fecal egg counts are performed before and 14 days after treatment; <95% reduction indicates resistance. The Baermann technique detects lungworm larvae, not strongyles. McMaster identifies eggs but not resistance status.

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE - North American Veterinary Licensing Examination Practice Test

NAVLE Small Ruminant Medicine (Sheep and Goats)