Many adjunctive surgical techniques have been proposed to decrease diarrhea following total colectomy with an ileoanal anastomosis. A previously proposed method of longitudinal muscle ablation in canine small intestine to produce an "artificial sphincter" and increase transit time after massive small bowel resections has been applied to puppies who have had a total abdominal colectomy and ileoproctostomy. Total abdominal colectomy with ileoproctostomy at the level of the peritoneal reflection was performed in 6 mongrel puppies, aged 6-8 weeks. Two control puppies died within 2 weeks of the procedure with overwhelming diarrhea. Four experimental animals had "sphincters" (circumferential excision of a 1 cm length of longitudinal muscle) placed 5 cm proximal to the ileoproctostomy anastomosis. The puppies with colectomy plus sphincter were followed from 14 months to two years postoperatively and had intestinal transit times of 3-4 1/2 hours comparable to unoperated littermates. Intermittent postoperative barium enemas were performed and gross and histologic examination of the sphincters were carried out at necropsy. This muscle ablation technique when used in puppies with total abdominal colectomy and ileoproctostomy controls diarrhea, allows survival with normal growth and does not result in proximal small bowel enteritis.