BCSE Large Animal Internal Medicine 4 — Questions and Answers
Question 1: A feedlot steer develops sudden onset neurologic signs including head pressing, aimless wandering, and blindness. Post-mortem reveals yellow-orange discoloration of the liver and brain. Which toxicosis is most likely?
- Lead poisoning
- Pyrrolizidine alkaloid toxicosis (Correct answer)
- Urea/non-protein nitrogen toxicity
- Nitrate toxicosis
Correct answer: Pyrrolizidine alkaloid toxicosis
Pyrrolizidine alkaloid toxicosis causes hepatic megalocytosis and progressive liver failure with secondary hepatic encephalopathy and characteristic yellowish liver discoloration.
Question 2: A 7-year-old warmblood gelding has a 2-month history of exercise intolerance, occasional muscle stiffness, and dark urine after light exercise. CK and AST are markedly elevated after exercise. A muscle biopsy shows abnormal polysaccharide accumulation. What is the diagnosis?
- Type 1 polysaccharide storage myopathy (PSSM1) (Correct answer)
- Recurrent exertional rhabdomyolysis (RER)
- Hyperkalemic periodic paralysis (HYPP)
- Malignant hyperthermia
Correct answer: Type 1 polysaccharide storage myopathy (PSSM1)
PSSM1 is caused by a GYS1 mutation causing excess glycogen and abnormal polysaccharide accumulation in muscle, confirmed by muscle biopsy with periodic acid-Schiff staining.
Question 3: In the diagnosis of Johne's disease (paratuberculosis) in cattle, which test has the highest sensitivity for detecting shedding animals in the subclinical phase?
- Serum ELISA antibody test
- Fecal PCR (Correct answer)
- Fecal culture
- Intradermal johnin test
Correct answer: Fecal PCR
Fecal PCR has higher sensitivity than fecal culture for detecting subclinical shedders, with results available in days rather than the weeks required for culture.
Question 4: Which of the following is the most common cause of esophageal obstruction (choke) in horses?
- Foreign body ingestion
- Poorly soaked sugar beet pulp or hay cubes (Correct answer)
- Esophageal neoplasia
- Esophageal stricture from prior trauma
Correct answer: Poorly soaked sugar beet pulp or hay cubes
Improperly soaked beet pulp or hay cubes that expand with saliva and water in the esophagus are the most common cause of choke in horses.
Question 5: Bovine leukemia virus (BLV) causes lymphoma that most commonly affects which organ system in adult cattle?
- Peripheral lymph nodes (multicentric form)
- Thymus
- Abomasum and lymph nodes (adult form) (Correct answer)
- Spinal cord
Correct answer: Abomasum and lymph nodes (adult form)
The adult (enzootic) form of BLV-associated lymphoma most commonly involves the abomasum, heart, uterus, and lymph nodes in cattle over 2 years of age.
Question 6: A 4-year-old Standardbred presents with intermittent hindlimb ataxia that worsens with the head elevated. Cervical radiographs show vertebral canal stenosis at C3-C4. What is the most likely diagnosis?
- Equine protozoal myeloencephalitis (EPM)
- Cervical vertebral stenotic myelopathy (Wobbler syndrome) (Correct answer)
- Equine herpesvirus-1 myeloencephalopathy
- Equine degenerative myeloencephalopathy (EDM)
Correct answer: Cervical vertebral stenotic myelopathy (Wobbler syndrome)
Wobbler syndrome causes proprioceptive ataxia that worsens with neck extension/elevation due to dynamic or static spinal cord compression at cervical vertebral articulations.
Question 7: Which treatment approach is recommended for a horse with confirmed right dorsal colitis associated with prolonged NSAID use?
- Increase NSAID dose and add proton pump inhibitor
- Discontinue NSAIDs, feed low-residue diet, and administer sucralfate (Correct answer)
- Perform surgical resection of the affected colon segment
- Administer corticosteroids and continue NSAIDs at reduced dose
Correct answer: Discontinue NSAIDs, feed low-residue diet, and administer sucralfate
Right dorsal colitis management requires immediate NSAID withdrawal, a low-residue diet to minimize fermentation trauma to the inflamed mucosa, and sucralfate to protect the ulcerated surface.
BCSE Large Animal Internal Medicine 4
A feedlot steer develops sudden onset neurologic signs including head pressing, aimless wandering, and blindness.
Post-mortem reveals yellow-orange discoloration of the liver and brain.
Which toxicosis is most likely?