Common Causes of Malabsorption in Horses

Inflammatory or infiltrative disorders

• Diffuse lymphosarcoma of the small intestine (alimentary lymphoma)

• Enteritis due to eosinophilic, lymphocytic-plasmacytic, or basophilic infiltrate

• Multisystemic eosinophilic epitheliotropic enterocolitis

• Granulomatous enteritis (inflammatory bowel disease)

• Lawsonia intracellularis (weanling foals, yearlings)

• Intestinal ischemia and damage due to migration of Strongylus vulgaris larvae, small strongyles, or Strongyloides westeri (foals) infection

• Cryptosporidia

• Postinfarction inflammation

• Amyloid-associated gastroenteropathy

• Multiple abscessation in the bowel

• Tuberculosis

• Histoplasmosis

• Intestinal Rhodococcus equi infection

• Invasive enterocolitis (Salmonella spp)

Biochemical or genetic abnormalities

• Congenital or acquired lactase deficiency (lactose intolerance)

• Dietary-induced enteropathy

• Monosaccharide transport defect

• Pancreatic exocrine insufficiencies

Diseases causing inadequate absorptive area

• Villous damage or atrophy due to viral infection (rotavirus, coronavirus) or bacterial enteritides in foals

• Cryptosporidiosis

• Intestinal resection

Cardiovascular disorders

• Congestive heart failure

• Intestinal ischemia

Lymphatic obstruction

• Lymphosarcoma

• Mesenteric lymphadenopathy

• Intestinal lymphangiectasia

• Abscessation

• Thoracic duct obstruction

Miscellaneous

• Drug-induced

• Heavy metal toxicosis

• Zinc deficiency