Effects of extensive resection of the small intestine in the pony.

Small intestinal resection (SIR) is not uncommonly done in surgical treatment of equine colic, but little is known about the long-term effects of SIR on horses and ponies. Twelve ponies, fed maintenance amounts of pelleted feed, were divided randomly into 4 treatment groups. D-Xylose absorption curves were recorded for each pony before surgical treatments were performed. Treatments consisted of control (ileal bypass) and 40%, 60%, or 80% SIR. D-Xylose absorption, serum electrolyte, and enzyme profiles for each animal were recorded once every 30 days for 180 days after surgical treatment, and the ponies were weighed every 2 weeks. The ponies then were necropsied and the remaining small and large intestine were examined. D-Xylose absorption values were depressed (P less than 0.05) in the ponies subjected to 40%, 60%, and 80% SIR as compared with the absorption values of the controls. The ponies with the 60% and 80% SIR lost body weight throughout the experimental period, whereas the controls and the ponies with 40% SIR maintained their base-line (presurgical manipulation) weight. Serum alkaline phosphatase activity was increased (P less than 0.05) in the ponies subjected to 60% and 80% SIR and significant biliary hyperplasia was present in those with 80% SIR. Extensive (greater than or equal to 60%) SIR severely compromised the capability of ponies to absorb nutrients and to derive adequate nutrition from a maintenance diet, resulting in changes in hepatic parenchyma and elevations in serum alkaline phosphatase. These changes are consistent with those reported in other species following SIR.