BACKGROUND: Intestinal lengthening (TL) is increasingly performed for the short bowel syndrome. Our aim was to evaluate the effect of TL on canine intestinal structure and function. METHODS: Two groups of 5 dogs had 75% distal intestinal resection. Twelve weeks later, serosal electrodes were placed in one group (RO) and tapering and lengthening of 10 to 15 cm distal intestine and electrode placement was performed in the other group (TL). Nutritional status and intestinal absorption, motility, and hormone release were assessed every 4 weeks for 12 weeks after the second procedure. RESULTS: The animals with the lengthening had diminished body weight (75% +/- 2% versus 81% +/- 4%, P < 0.05) and albumin levels (2.4 +/- 0.2 g/dL versus 2.9 +/- 0.5 g/dL, P < 0.05) and impaired absorption (stool fat 18% +/- 6% versus 10% +/- 3%, P < 0.05) compared with those that had undergone resection alone. The intestinal adaptive response was blunted in the TL group (villus height 328 +/- 90 microns versus 410 +/- 36 microns, P < 0.05). Transit time was prolonged 4 and 8 weeks (19 +/- 6 min and 18 +/- 5 min, respectively, versus 11 +/- 3 min, P < 0.05) after TL. Myoelectrical recordings showed a drop in slow wave frequency and impaired migration of Phase III of the migrating motor complex within the tapered and lengthened segments (P < 0.05). Both fasting and postprandial serum gastrin levels were two times greater in the TL group (P < 0.05). Enteroglucagon levels were increased after resection alone; this increase was attenuated by more than 50% in the TL group (P < 0.05). The somatostatin response to feeding was substantially greater in the TL animals. CONCLUSIONS: TL impairs nutritional status and intestinal absorption and adaptation following massive resection. The changes in absorption and transit may be related, in part, to motor disruption and hypergastrinemia. The impaired adaptation is possibly related to decreased enteroglucagon and increased somatostatin levels.