Changes in gastrointestinal motility after subtotal colectomy in dogs

Purpose. This study was conducted to examine recovery from diarrhea after subtotal colectomy by observing changes in gastrointestinal motility, neuropeptides, and autonomic nerves in the enteric nervous system in dogs. Methods. The moisture volume of intestinal matter recovered from the ileal side of the anastomosis was defined as the diarrhea index. Gastrointestinal motility was measured using strain gauge force transducers (SG) for 24 weeks after subtotal colectomy. Immunohistochemical changes in neuropeptides in the residual intestine, acetylcholinesterase activation of cholinergic fibers, and fluorohistochemical changes of adrenergic fibers in the myenteric plexuses were evaluated. Results. The digestive tract transit time returned to normal in the early postoperative period, but decreased moisture volume was seen in the intestinal matter after 8 postoperative weeks. Migrating contraction waves propagating beyond the site of anastomosis, signaling recovery of intestinal motility, were noted after 8 postoperative weeks, corresponding to reconstruction of cholinergic fibers in the anastomotic section. Transient activation of vasoactive intestinal polypeptide was seen in the residual intestine, but this had normalized by the eighth postoperative week. Lengthened villi in the residual intestine were also seen after 8 postoperative weeks. Conclusion. The decreased moisture volume in the intestinal matter is due to the improvements we observed in the eighth postoperative week.