Merck Manual

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Noninfectious Diseases of the GI Tract in Animals


Alex Gallagher

, DVM, MS, DACVIM (SAIM), University of Florida

Last full review/revision Oct 2020 | Content last modified Oct 2020

The major causes of noninfectious disease of the GI tract include:

  • dietary issues (eg, feed overload, intolerance, allergy)

  • dietary indiscretion, including foreign body ingestion

  • GI obstruction

  • mucosal injury (eg, gastric ulcers, inflammatory bowel disease, neoplasia)

  • intestinal dysbiosis

  • enzyme deficiencies

  • congenital defects

GI manifestations such as vomiting and diarrhea may develop secondary to systemic or metabolic diseases such as kidney disease, liver disease, or 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.

For More Information

  • Also see pet health content regarding digestive disorders of cats, dogs, and horses.

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