Horses with colic appear restless and uncomfortable and may look at or paw their abdomen. In more severe cases animals may recline and stand repeatedly, or roll and thrash on the ground. Heart and breathing rates may increase, and the horse may sweat. A veterinarian should be called as soon as these signs are recognized. As with founder, colic can be caused by many different conditions, including twists of the intestine, parasitic worms, disease of any abdominal organ, and diet.
Diet-related causes include gas colic, impaction colic, sand colic, and spasmodic colic. Gas colic can result from over consumption of lush grass feed, which causes excessive gas production in the intestine.
Impaction colic, due to blockage of the intestine, can result from excessive consumption of grain, lush pasture, lack of water in the diet, or consumption of foreign material. Ingested grain or grass may produce products that suppress the normal movement of the intestine, while foreign material, such as wood chewed from fences, may become lodged in the intestine and block passage of gut contents.
Sand colic can occur when horses are fed on the ground where the soil is sandy or when horses develop the vice of eating soil. Horses eating on sandy soils are often fed soluble-fiber bulk-inducing agents such as psyllium hydrophilic mucilloid (Metamucil or Modane) to bind the sand and help it pass out of the gastrointestinal tract. Wheat bran has been used by some for this purpose but it is not nearly as effective. Finally, spasmodic colic describes increased numbers of bowel movements and episodes of pain following sudden changes in environmental temperature, diet, or activity level. Diet-related causes of colic, like those of other diet-related diseases, are more successfully prevented than treated.