Extensive large colon resection in the pony. II. Digestibility studies and postmortem findings.

The nutritional implications and adaptive processes resulting from resection of 75% of the length of the large colon in ponies were investigated. Ten ponies in good physical condition were divided into two groups: six in the experimental group and four in the control group. During the sixth postoperative month, two digestibility studies were conducted, and phosphate fractional renal excretion and serum biochemical profiles were determined in both groups. The ponies (N = 10) were euthanized six months postoperatively, and gross and histopathological examinations were performed. Results of the serum biochemical profiles, phosphate fractional renal extraction and digestibility studies showed no statistically significant difference between groups except for the serum phosphate concentration. However, large colon resection was associated with hypophosphatemia in three of the six ponies and produced an overall significantly lower phosphate concentration in the experimental ponies. This hypophosphatemia suggests that some dietary modifications may be needed postoperatively in ponies or horses undergoing this surgical procedure. Postmortem examination and histopathological examination failed to demonstrate differences between groups. Adaptive mechanisms, specifically mucosal hypertrophy or hyperplasia, were not observed.