ABSTRACT
Large-Colon Tympany Prevalence, Etiology, Risk Factors Large-colon tympany (gas colic, spasmodic colic) is the most common reported cause of colic in horses.1-3 This condition is thought to result from excessive gas fermentation in the colon, resulting in distention and pain. In one study evaluating risk factors for simple colonic obstruction and distention colic in horses (including large-colon impaction), the following factors were associated with an increased risk for this type of colic:4 crib-biting or windsucking, increasing number of hours spent in a stable, recent change in regular exercise program, absence of administration of ivermectin or moxidectin anthelmintic in the previous 12 months, and a history of travel in the previous 24 hours. An association between tapeworm infestation and spasmodic colic has been demonstrated.5 Horses fed a hay and grain diet containing a large amount of soluble carbohydrates and less fiber had decreased water content in ingesta and increased gas, which predispose to gas colic.6 Although large-colon tympany can be self-limiting, it is thought to precede large-colon displacements; therefore, identification of risk factors in affected horses may help to decrease the risk of future occurrences and the development of displacements.
