Merck Manual

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Common Causes of Malabsorption in Horses

Common Causes of Malabsorption in Horses

Type

Examples

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