A 20-year-old 407-kg (895-lb) Appaloosa gelding was evaluated at a veterinary teaching hospital because of tachycardia and tachypnea. Seven hours prior, the horse was inappetent and lethargic and had bilateral jugular venous pulsation. There was no known toxin exposure. The horse was treated with flunixin meglumine and referred for evaluation.
Physical examination revealed dull mentation, dark pink mucous membranes with a prolonged capillary refill time, moderate tachypnea (respiratory rate, 46 breaths/min), severe tachycardia (heart rate, 120 beats/min), bilateral jugular pulsations to the level of the ramus of the mandible, and hypokinetic digital and facial arterial pulse quality. Gastrointestinal borborygmi were