Influence of myectomy, ileal valve, and ileal reservoir on the ecology of the ileum.

Fecal bacteriology, fecal volatile fatty acids, and ileal mucosal morphology were studied in dogs after ileoanal anastomosis alone, ileoanal anastomosis and myectomy, ileoanal anastomosis and myectomy with ileoileal valve, and ileoanal anastomosis with duplicated (J) ileal reservoir. The ratio of anaerobes to aerobes was significantly less in stool from dogs which had undergone ileoanal anastomosis compared with each of the other three groups (P less than 0.01). The numbers of streptococci and clostridia both were significantly less in stool from dogs with ileoanal anastomosis alone than in any other group. The concentrations of fecal acetic and propionic acids were significantly less in dogs with ileoanal anastomosis alone than in any other group (P less than 0.05), but there were no significant differences in the concentrations of fecal butyric or valeric acids. The severity of mucosal inflammation and degree of villous atrophy were more marked in the ileum of J reservoirs (P less than 0.01), and the percentage of stool retained after defecation was greater (P less than 0.05) in dogs with J reservoirs than in any other group. Therefore, the use of myectomy resulted in significant changes in the ecology of the distal ileum although changes typical of pouchitis were seen only in dogs with J reservoirs.