Caecocolic ligament hypoplasia in a Thoroughbred filly with volvulus of the large colon

Abstract

SummaryAn 11‐month‐old Thoroughbred filly was referred to the hospital with signs of severe abdominal pain unresponsive to medical treatment. Upon arrival, the filly had a heart rate of 60 beats/min, pink mucous membranes and continued to show severe colic signs despite sedation. Due to the severity of colic signs, general anaesthesia was induced immediately. Exploratory celiotomy revealed a large colon volvulus of more than 360 degrees and hypoplasia of the caecocolic ligament between the caecum and right dorsal colon. The large colon volvulus was corrected, and the filly recovered uneventfully from general anaesthesia. Post‐operative treatment included intravenous fluids and intravenous lidocaine continuous rate infusion, parenteral nutrition, systemic antibiotics, nonsteroidal anti‐inflammatories, gastroprotectants and restricted feeding. The filly experienced several post‐operative complications associated with severe enterocolitis including pyrexia, leukopenia and diarrhoea but made a full recovery and was discharged to the farm after 16 days of hospitalisation. Long‐term follow‐up was available for 22 months after surgery without further reports of colic and the filly had entered race training. Hypoplasia of the caecocolic ligament in association with colic in horses has rarely been reported in the equine literature. To date, only two further case reports of young horses with large colon volvulus and hypoplasia of the caecocolic ligament have been published. In contrast to the presenting case, several other mesenteric abnormalities were present in these two cases in addition to the hypoplastic caecocolic ligament and both horses were eventually euthanised. The pathogenesis of hypoplasia of the caecocolic ligament remains unclear but may include the disruption of early stages of embryogenesis. An abnormal caecocolic ligament has been suggested to potentially predispose horses to large colon volvulus. The presenting case indicates that as an isolated abnormality, a hypoplastic caecocolic ligament may not result in reduced long‐term survival in horses with large colon volvulus.