A 6-year-old thoroughbred gelding presented to the gross pathology service of the Cornell Animal Health Diagnostic Center for necropsy. The horse suffered from an acute colic that resulted in sudden death. Its abdomen was notably distended, and the gastrointestinal tract appeared grossly edematous with diffusely dilated regions filled with gas and liquid. No solid material was present in the stomach, small intestine, cecum, colon, or rectum. Petechial hemo1Thages and ecchymoses were found on the serosal surface of the cecum and colon. Mucosa! necrosis was seen in two portions of colon and thrombi were present in the mteries supplying blood to these pmtions of bowel. Three !-cm-long nematodes were recovered from the mesenteric artery and were later identified as Strongylus vulgaris. This report highlights the pathological findings of a case of fatal verminous equine mteritis, and reviews the life cycle, diagnosis, treatment and control of S. vulgaris in the horse.