Septic peritonitis associated with caudal myotomy in a Tennessee walking horse

A 2-year-old Tennessee Walking Horse colt was admitted for evaluation of signs of abdominal pain, inappetence, and constipation of 5 days' duration. Two days prior to the onset of signs, the owner had cut the sacrococcygeal muscles as part of a tail-setting procedure. On examination, the horse was febrile and lethargic, and intestinal sounds were not heard on auscultation. Results of peritoneal fluid analysis were indicative of peritonitis. The horse continued to deteriorate and died despite treatment with antimicrobials, flunixin meglumine, and balanced electrolyte solution. At necropsy, the peritoneal cavity contained approximately 20 L of serosanguineous fluid. One of the myotomy wounds was filled with yellow-green material that extended from the base of the tail along the ventrolateral aspect of the rectum and into the peritoneal cavity. Escherichia coli was isolated from the myotomy site and peritoneal fluid.