Factors affecting outcome following proximal and distal intestinal resection in the dog: An examination of the relative roles of mucosal adaptation, motility, luminal factors, and enteric peptides

In the clinical setting, resection of the ileum results in an inferior functional outcome compared to jejunal resection. This may be related to a greater adaptive capacity of the ileum, intrinsic structural and functional differences, or regional differences in motor and hormonal function. Our aim was to evaluate the relative contributions of these factors to functional outcome after resection of the proximal or distal intestine. Twenty-four dogs underwent either intestinal transection or 50% resection of the proximal or distal intestine. Studies (nutritional status, absorption, adaptation, motility, peptide levels) were performed every four weeks until the animals were killed at 12 weeks. Caloric intake was similar in all four groups. Weight loss was greater and more sustained after distal resection (DR). Serum cholesterol levels decreased significantly only in the DR group. While stool weight and moisture were similar, the DR animals had persistent, significant steatorrhea. Intraluminal anaerobic bacteria and SCFA concentrations were significantly greater in the ileum but were not influenced by resection. Intestinal remnant length increased to a greater extent after proximal resection (PR), but circumference increased to a similar extent after both resections. Villus height and crypt depth increased significantly only after PR. MMC frequency was similar in all four groups. In the DR animals 26% of migrating motor complexes (MMCs) originated within the remnant. The jejunal remnant of these animals had a dominance of cluster activity similar to the intact distal ileum. Following PR, the postprandial motilin response was decreased. After DR, there were transient increases in neurotensin and PYY. Of the various factors evaluated, mucosal adaptation and the intestinal motor response appear most likely to explain the inferior nutritional and absorptive outcome associated with resection of the distal small intestine.