Impactions of the small and large intestines.

Impactions of the small and large intestines are frequently diagnosed as the cause of colic in horses. An impaction is an accumulation of dehydrated ingesta in a portion of the digestive tract, typically at sites where the intestinal diameter decreases. The specific pathogenesis for impactions is not fully understood, although risk factors have been identified for several types of impactions. Treatment for impactions includes withholding feed until the impaction passes, rehydrating the ingesta, and, if necessary, administering analgesic agents. In severe cases, surgery may be necessary to relieve the impaction. This article discusses clinical signs, diagnosis, treatment (both drug and surgical options), and prognosis for impactions of the duodenum, jejunum, ileum, cecum, and small and large colons in horses.