Right dorsal colon fistulas, 2.5 cm in diameter, were created in 2 healthy ponies, using a 2-stage surgical procedure. The first stage consisted of resection of portions of the 16th and 17th ribs on the right side, followed by surgical creation of a 6- to 8-cm-diameter adhesion between the right dorsal colon and the body wall. Fistulas were created approximately 2 weeks after the first surgery by sharp dissection through the adhesion into the lumen of the colon. The fistulas have been satisfactorily maintained for > 2 years by de Pezzer catheters (45 F). Ponies with fistulas have been used for gastrointestinal experiments.

To provide long-term gastric fistulas for collection of third-compartment gastric contents, Janeway mucosal tube gastrostomy was performed, using a gastrointestinal stapling instrument, in 6 castrated adult male llamas. Mean operative time (+/- SEM) was 65 +/- 4.16 minutes. All llamas survived the 6-week study period. Of the 6 llamas, 5 did not have signs of abdominal pain and returned to preoperative food consumption amounts within 36 hours. One llama had mild intermittent signs of abdominal pain daily for 7 days before returning to preoperative amount of food consumption. All gastrostomies leaked small amounts of gastric contents around indwelling 6- to 8-mm cannulas at the skin surface. Gastric contents did not leak when cannulas were dislodged from gastrostomy stomas. Replacement of cannulas was rapid and easy. Gravity-flow sample collection was best accomplished through 8-mm cannulas. Mean (+/- SEM) weight loss was detected in all llamas (15 +/- 3 kg) and was associated with frequent nonfeeding and stress of sample collection. Gross necropsy findings were unremarkable in 5 of 6 llamas. All mucosal tube gastrostomies were patent, and there was no evidence of peritonitis. One llama had a single fibrous adhesion connecting the operative site with the ascending colon. Histologically , small (2.5- to 15-mm diameter) partial-thickness mucosal erosions identified at the tube gastrostomy-gastric wall junctions may have been associated with indwelling gastric cannulas. The Janeway gastrostomy was generally well tolerated in the llamas and should be considered as a useful long-term fistulation technique.