Enteroliths are stony concretions that can develop in the large intestine of the horse. They may grow to the size of a bowling ball, but seem to occur only in horses from certain regions of the United States. The cause of these concretions in unknown but may be related to diet or water content of feed. Horses may pass smaller enteroliths in the feces on their own accord, but larger eneroliths reguire surgery to be removed. Some have advocated a cup of vinegar once a day as a preventive measure but the efficacy of this method has not been determined.

            Ingestion and deposition of sand in the large intestine may lead to irritation and impaction of the large colon resulting in signs of colic. Other signs associated with this problem include weight loss and intermittent diarrhea. Attempts should be made in sandy, soiled areas to feed horses off the ground. In addition, the feeding of psyllium fiber may help to decrease and clean out sand buildup in susceptible horses in highrisk areas. If sand buildup is severe, surgery may be necessary to alleviate the problem.

            Poor or ineffective motility of the large intestine is reflected in an inability of the bowel to push feed contents through to the anus at a normal pace. The resulting functional obstruction will produce signs of colic similar to those caused by a physical obstruction of the bowel, with the only difference that functional obstructions are much more difficult to diagnose and the outcome is very poor.