Growth of neomucosa has been investigated as a means to increase intestinal surface area in the short-bowel syndrome. Functional neomucosa grows over patched intestinal defects, but the effect of the patching procedure on absorption is unknown. The purpose of this study was to determine morphologic and nutritional responses to intestinal patching after resection. Fifteen dogs (13 to 19 kg) underwent either 75% resection of the small intestine (control group, n = 5), simultaneous resection and patching of the intestinal remnant with colon serosa (simultaneous group, n = 5), or resection with patching 12 weeks later (delayed group, n = 5). Caloric intake was standard in the three groups. Animals were killed 40 weeks after resection or patching. At that time, defects were 95% covered with neomucosa in both patched groups. Intestinal remnant length increased significantly in controls (139 +/- 20% initial length) compared to the simultaneous group (99 +/- 6%, p less than 0.05) but not to the delayed group (119 +/- 11%). Villous height of intestinal mucosa was greater in the control and delayed groups than in the simultaneous group (714 +/- 36 and 624 +/- 111 versus 535 +/- 54 micron, p less than 0.05). Fasting gastrin levels were significantly greater in patched animals than after resection alone (p less than 0.05). Intestinal transit by barium meal was significantly longer in patched animals (18 +/- 7 minutes versus 11 +/- 6, p less than 0.05). Body weight and serum albumin level were significantly lower in patched animals at death. Fecal weight, moisture, and fat excretion were significantly increased in the simultaneous group. Although intestinal patching results in the growth of neomucosa and prolonged transit time, it has a deleterious effect on absorption and nutritional status. In part, this may be related to inhibition of intestinal adaptation and gastric hypersecretion in patched animals.