420 CVJ / VOL 48 / APRIL 2007 Case Report Rapport de cas Congenital colonic malformation (“short colon”) in a 4-month-old standardbred foal Judith B. Koenig, Alexander Rodriguez, J. Keith Colquhoun, Henry Stämpfli Abstract — During exploratory laparotomy of a foal with colic, a congenital abnormally developed large colon was identified incidentally. Long-term follow-up showed that the colt was more prone to gas-colic with diet and exercise changes than were other horses, due possibly to the short colon. Résumé — Malformation congénitale du côlon (côlon court) chez un poulain Standardbred âgé de 4 mois. Au cours d’une laparotomie exploratrice chez un poulain atteint de colique, une malformation congénitale du gros côlon a été identifiée de façon fortuite. Un suivi à long terme a montré que le poulain était davantage sensible aux coliques gazeuses reliées à des modifications d’alimentation et d’exercices que les autres chevaux, possiblement à cause du côlon court. (Traduit par Docteur André Blouin) Can Vet J 2007;48:420–423 A 4-month-old standardbred colt was examined by a pri- vate veterinary practitioner (KC) for mild colic, which responded to treatment with flunixin meglumine. No abnor- malities were observed for the following 4 d. Suddenly, the colt started to show signs of severe colic. On physical examination, a heart rate of 80 beats per minute (bpm), hyperemic mucus membranes, and decreased gastrointestinal sounds were noted. No gastric reflux was obtained via nasogastric intubation. The colt was then treated with flunixin meglumine, xylazine, and butorphanol, IV. He continued to display severe colic signs and was referred within 1 h after onset of the signs to the Ontario Veterinary College, Veterinary Teaching Hospital, for further evaluation. Case description On presentation, the colt was in moderate, continuous pain and his abdomen was mildly distended. His heart rate was 88 bpm, respiratory rate 35 breaths per minute, and rectal temperature 37.5°C. Mucus membranes were hyperemic with a capillary refill time of 3 to 4 s. The distal extremities were cold to the touch. Based on the clinical examination, dehydration was estimated to be moderate. A jugular catheter was placed, IV, on the left side, and fluid therapy with lactated Ringer’s solu- tion was initiated (50 mL/kg BW/h). On auscultation of the abdomen, decreased gastrointestinal sounds were noted in all 4 quadrants. Nasogastric intubation did not yield any gastric reflux. Initial packed cell volume, total plasma protein value, serum electrolyte levels, and venous blood gas levels were within normal reference ranges. On transabdominal ultrasonography, multiple loops of fluid-filled hypermotile small intestine were observed and a moderate amount of free peritoneal fluid was also identified. Abdominocentesis did not yield any peritoneal fluid. Within 1 h of admission, the colt received xylazine (Rompun; Bayer Agriculture Division Animal Health, Toronto, Ontario), 0.3–0.5 mg/kg body weight (BW), IV, q20min for 1 h and 1 dose of butorphanol (Torbugesic; Ayerst, Montreal, Quebec), 0.05 mg/kg BW, IV. However, the colt remained in pain despite the administration of analgesics and his heart rate increased from 88 to 100 bpm. Based on these findings, an exploratory laparotomy was recommended to the owner in order to further evaluate the origin of abdominal pain. Differential diagnoses at that time included small intestinal obstruction or small intestinal inflammation (proximal enteritis). Sodium penicillin (Penicillin G Sodium; Novopharm, Toronto, Ontario), 20000 IU/kg BW, IV, q6h, and gentami- cin (Gentamicin sulfate; The Veterinary Pharmacy, Guelph, Ontario), 6.6 mg/kg BW, IV, q24h, were administered pre- operatively. The foal was subsequently placed in dorsal recum- bency under general inhalation anesthesia. A ventral midline celiotomy was performed and the peritoneal cavity explored. The small intestine was moderately hyperemic with several areas of petechiation (Figure 1), consistent with enteritis of the small intestine. The large intestine was exteriorized and found to be anatomically abnormal. The right ventral colon originated from the cecum and continued as the left ven- tral colon, which, in turn, continued as the transverse colon (Figure 1). The ventral colon was identified by its having a uniform diameter and 4 taeniae all the way through. Neither a pelvic flexure nor a dorsal colon was identified. The body Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, Ontario N1G 2W1 (Koenig, Rodriguez, Staempfli); Colquhoun & Associates Equine Veterinary Services, RR#5, Rockwood, Ontario N0B 2K0 (Colquhoun). Address all correspondence to Dr. Judith Koenig; e-mail: jkoenig@uoguelph.ca Reprints will not be available from the authors.