A 6 year old Thoroughbred gelding presented to the Cornell University Large Animal Emergency Service for an approximately 12 hour history of colic. At presentation, the patient appeared moderately painful. Gut sounds were absent in all quadrants. On ultrasound, the wall of the large colon was thickened and edematous, and colonic vessels were apparent adjacent to the body wall. At surgery, a 360° large colon volvulus at the base of the cecum was identified and reduced following gas decompression of the large colon. The large colon was deemed viable and left in situ. Post-operatively the patient was treated with standard post-operative analgesics, fluids, and antibiotics. Additionally, treatment for endotoxemia was pursued. The patient had bloodwork changes consistent with endotoxemia for 3 days following surgery, but did not develop any significant complications. He was discharged 6 days after surgery and has been doing well since discharge as per the owner. This case report will describe the full workup and treatment of this patient with a large colon volvulus. Treatment options for horses with large colon volvulus, including enterotomy, large colon resection and anastomosis, and colopexy will be described. Additionally, endotoxemia management and potential complications will be discussed.