Please work through this case. Consult standard textbooks of Equine Medicine to supplement the information provided in class. (Examples: current Veterinary Therapy-Equine, Equine Internal Medicine (Reed and Bayly) or Large Animal Internal Medicine (Smith). The exercise is intended to "stretch" your thinking. Case discussion among students is encouraged.
In July, a five year old 400 kg Quarter Horse stallion has acute, voluminous, projectile, watery diarrhea of 10 hours duration. He is kept on a breeding farm with 30 other horses. The farm manager tells you that each summer, 2 or 3 horses on the farm develop diarrhea; however, previous cases have never been this severe. The history also indicates that all horses have been dewormed with ivermectin twice in the last 2 months. There was an outbreak of respiratory disease the previous week and several horse, including the stallion, are being treated with SMZ TMP (potentiated sulfa).
At this point, you would
like to perform a physical exam and run some diagnostic tests.