We report one such case which was diagnosed intraoperatively as left dorsal colon volvulus due to multiple mesenteric abnormalities. A 17-year-old castrated male horse was taken to the Tehran University Veterinary Hospital for treatment of metacarpal wound accompanied by severe abdominal distension and acute colic. The treatment and measurement were taken for a month, and the prepared biopsy indicated that the healing trend was obvious. Unfortunately, prior to discharge, the clinical colic manifestations emerged and the animal suddenly died. Dilated large intestine was palpated per rectum and a ventral midline exploratory laparotomy was performed, a complete volvulus of the ascending colon was identified with multiple mesenteric anomalies of unknown aetiology. The pathologic changes observed in this study accurately reflect those changes reported in horse with naturally occurring colonic volvulus and can serve as a reference for subsequent studies on attenuating bowel injury. The present study results can be used to make a scientific assessment of prognosis in the pre-operative, operative, and post-operative management of horses with large colon volvulus.