Colic is one of the most common problems horses experience, competing only with lameness for the dubious distinction of being the most likely’ potentially serious ailment a horse may encounter at some time during its lifetime. As with lameness, there are many different types of, and causes for colic, each requiring specific treatment. For this reason, there is no single effective “colic drug.”
Colic is a general term used to describe abdominal pain in the horse, in other words a belly-ache. The abdominal cavity contains the gastrointestinal tract (GI Tract) from stomach to rectum; the liver; the urinary tract containing kidneys, ureters, bladder and urethra; and the reproductive organs in the mare. It is lined by a thin membrane called peritoneum. Although ‘true colic’ refers to pain relating to the GI Tract or peritoneum, pain in the liver, urinary tract and reproductive organs may appear similar. Some diseases unrelated to the abdominal cavity, such as laminitis “founder” may also be mistaken for colic.
The severity of signs shown by horses with colic is highly variable. Some animals may behave very violently, i.e., rolling, kicking and getting cast, others may simply appear dull and listless. Most cases of colic do resolve with appropriate medical therapy, although some animals may require surgery. The sooner surgery is performed, the better the prognosis for survival. Thus all animals with colic should be examined by a veterinary surgeon immediately, if at all possible.
Diet-related types of colic include gas colic, impaction colic, sand colic, and spasmodic colic. Gas colic could be caused, among others, by over consumption of lush grass feed, resulting in excessive gas production in the intestine. Impaction colic, due to blockage of the intestine, can result from sudden changes in feed, excessive consumption of grain or lush pasture, dehydration, or by ingestion of foreign material. Ingested grain or grass may produce by-products that suppress the normal movements of the intestinal wall, while foreign material, such as wood chewed from fences (sawdust), can become lodged in the intestine and block the passage of gut contents. Sand colic occurs when horses are fed on the ground in areas where the soil is sandy, or when they develop the vice of eating soil. Spasmodic colic is characterized by an increased number of bowel movements and episodes of pain following sudden changes in environmental temperature, diet, or activity level. These diet-related causes of colic, like those of other diet-related disorders, are more successfully prevented than treated.