Partial colectomy for treating acquired megacolon in long-tailed macaques.

A syndrome presenting as gross abdominal distension and diagnosed as acquired megacolon was observed in five adult female long-tailed macaques. Gastrointestinal signs included diarrhea, mucus in the stool, anorexia, and failure to pass stool, with repeated episodes of extreme abdominal distension and accumulation of gas and feces in greatly enlarged colons. Medical management was unsuccessful. A partial colectomy with a standard end-to-end colonic anastomosis was performed to remove the section of distended colon in each animal. Histologically, affected colons had degeneration and fibrosis, primarily in the longitudinal layer of the lamina muscularis. Hemograms, serum chemistries, and histopathologic features were not diagnostic of a specific etiology for megacolon. Four of five animals had undergone at least one obstetrical surgery. Two of these had the first episode of colonic distension within 3 days postoperatively. Intra-abdominal adhesions were noted during exploratory surgery in all animals. Three of five had colonic volvulus observed during colectomy. Recovery post-colectomy was uneventful and animals remained free of clinical signs of megacolon.