Noninfectious Diseases of the GI Tract
The major causes of noninfectious disease of the GI tract include dietary overload or indigestible feeds, chemical or physical agents, obstruction of the stomach and intestines caused by the ingestion of foreign bodies or by any physical displacement or injury to the GI tract that interferes with the flow of ingesta, enzyme deficiencies, abnormalities of the mucosa that interfere with normal function (eg, gastric ulcers, inflammatory bowel disease, villous atrophy, neoplasms), and congenital defects. GI manifestations such as vomiting and diarrhea may develop secondary to systemic or metabolic diseases such as uremia, liver disease, and hypoadrenocorticism. The causes are uncertain in several diseases, including abomasal ulcers in cattle, gastric ulcers in pigs and foals, gastric torsion in dogs, and acute intestinal obstruction and displacement of the abomasum in cattle. In noninfectious diseases of the GI tract, usually only a single animal is affected at one time; exceptions are diseases associated with excessive feed intake or poisons, in which herd outbreaks are common.