Development of a porcine Roux-en-Y gastric bypass survival model for the study of post-surgical physiology

Background: Rodents have been used to examine physiologic changes after bariatric surgery, but differences in gastric/vagal anatomy may limit their utility. Swine may be a more appropriate animal model because of anatomic and physiologic similarities to humans. The aim of this study was to establish a survival model of Roux-en-Y gastric bypass (RYGBP) in swine and to evaluate its potential in studies of physiology. Methods: 13 miniature swine, 5 Yucatan [26.4 +/- 1.6 kg], 4 Hanford [28.3 +/- 0.6 kg] and 4 other breed [54.9 +/- 6.2 kg] underwent open RYGBP, and were kept alive to 30 (n=4), 60 (n=1) or 90 (n=2) postoperative days. Results: 4 early animals had staple-line leakage within 7 days from surgery and 1 animal experienced unmanageable pain at 42 days after surgery. One animal experienced immediate cardiopulmonary collapse. 58% of animals survived to their projected end-point. Necropsy of 1 animal at its 90-day endpoint revealed a gastro-gastric fistula. Anatomic features in swine that differ from humans, such as thick perigastric membranes, required adjustment to the standard RYGBP technique used in humans to achieve satisfactory results. Caloric intake decreased in some but not all animals, and was linked to feeding regimen. By postoperative day 30, animals weighed 5.7-29.1% less than their projected, non-operative weight. Serum assays of ghrelin and PYY were conducted, with results consistent with the procedure. Conclusions: The use of swine as a model for bariatric surgery has promise, but also has associated piffalls that must be addressed for this to be an effective model.