ISSN 2398-2977      

Chronic inflammatory bowel disease


Graham Munroe

Synonym(s): CIBD


  • Group of chronic infiltrative enteropathies including granulomatous enterocolitis , eosinophilic enterocolitis and lymphocytic-plasmacytic enteritis of largely unknown pathogenesis.
  • Cause: small intestinal mucosal and submucosal infiltration with abnormal cells   →   malabsorption syndromes whilst the rarer large intestine involvement causes chronic diarrhea. This infiltration may be caused by an abnormal immune response to an infectious agent or dietary antigens.
  • Signs: chronic weight loss +/or diarrhea may be accompanied by low-grade or recurrent abdominal pain, inappetence, pyrexia, peripheral edema and skin lesions.
  • Diagnosis: involves histopathology of intestinal biopsies taken at surgery or PM, or rectal biopsy, and is based on the degree of inflammation present and the main type of leukocyte cell infiltrating the gut lining. Blood hematology and biochemistry, rectal examination, transrectal and transabdominal ultrasonography, abdominocentesis.
  • Treatment: long-term corticosteroid therapy may be useful but may be required to be life-long; dietary changes; parasite control.
  • Prognosis: guarded to poor.



  • Granulomatous enterocolitis has been associated with mycobacterial infections (M. paratuberculosisandM. avium    Mycobacterium spp  ), fungal infections (Aspergillus fumigatus  Aspergillus fumigatus  ,Histoplasma capsulatum  Histoplasma spp  ) and Hairy Vetch poisoning. Most cases are idiopathic and may represent an abnormal host inflammatory reaction to intestinal bacteria or diet. Aluminium exposure via invading micro-organisms, especially parasites, has also been associated with granulomatous enteritis in the horse.
  • Food allergies and parasitic infestations have been suggested as causes of eosinophilic enterocolitis.
  • Genetic and/or familial causes are recorded in humans and may be relevant to the horse, especially in the Standardbred.


  • Collective term for a group of chronic infiltrative enteropathies which are poorly defined in the horse.
  • Includes granulomatous enterocolitis, eosinophilic enterocolitis and lymphocytic-plasmacytic enteritis:
    • Granulomatous forms are characterized by lymphoid and mcarophage infiltration of the mucosal lamina propria with variable amounts of plasma and giant cells.
    • Eosinophilic enteritis/enterocolitis involves diffuse infiltration of the small intestinal/colon mucosa with eosinophils and lymphocytes (DEE). A proportion of these may also have eosinophilic infiltration of the skin, liver, pancreas, oral cavity, esophagus, lungs and mesenteric lymph nodes (multisystemic eosinophilic epitheliotrophic disease). In some eosinophilic cases there may be single or multiple focal circumferential or plaque-like constrictions, usually in the small intestine, that can lead to acute abdominal pain symptoms (idiopathic focal eosinophlic enteritis).
    • Lymphocytic/plasmacytic enteritis is characterized by excessive infiltration of lymphocytes and plasma cells in the lamina propria of the gut without other changes.
  • Pathogenesis is largely unknown but may represent an immune-mediated reaction to various dietary antigens and infections:
    • In eosinophilic enteritis it is thought to be a type 1 hypersensitivity reaction to dietary, parasitic or inhaled antigens.
    • Recently gluten intolerance has been suggested as a cause with some cases showing raised gluten-dependent antibodies.
    • Some clinicians believe lymphocytic/plamacytic enteritis may be an early form of intestinal lymphosarcoma. Indeed the latter is sometimes considered as an inflammatory bowel disease.
  • Infiltration can occur in the small intestine   →    protein-losing enteropathy and malabsorption. If the large intestine becomes involved, especially in eosinophilic forms, chronic diarrhea ensues.
  • Villous atrophy is common in the granulomatous form with the ileum most commonly affected    →   loss of absorptive surface area + mucosal cell junctions enlarge allowing net loss of fluid and protein.
  • Mucosal ulcerations caused by the inflammatory infiltrates further contribute to transudation into the lumen.
  • Chronic inflammation of the large intestine causes fluid secretion into the bowel and is the main reason for the diarrhea.
  • Infectious causes of inflammatory bowel disease such asLawsonia intracellularis  Lawsonia intracellularis   andRhodococcus equi  Rhodococcus equi  .


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Makinen P E et al (2008) Characterisation of the inflammatory reaction in equine idiopathic focal eosinophilic enteritis. Equine Vet J 40 (4), 386-392 PubMed.
  • Divers T J, Pelligrini A & McDonough S (2006) Diagnosis of inflammatory bowel disease in a Hackney pony by gastroduodenal endoscopy and biopsy and successful treatment with corticosteroids. Equine Vet Educ 18 (6), 284-287 Wiley Online.
  • Mair T, Pearson G R & Divers T J (2006) Malabsorption syndromes in the horse. Equine Vet Educ 18 (6), 383-392 VetMedResource
  • Stampfli H & Oliver O E (2006) Chronic diarrhea and weight loss in three horses. Vet Clin North Am Equine Pract 22, e2735 PubMed.
  • Tamzali Y (2006) Chronic weight loss syndrome in the horse: a 60 case retrospective study. Equine Vet Educ 18 (6), 372-380 VetMedResource.
  • McCue M et al (2003) Dexamethasone for treatment of multisystemic eosinophilic epitheliotropic disease in a horse. J Am Vet Med Assoc 223 (9), 1320-1323 PubMed.
  • Schumacher J, Edwards J F & Cohen N D (2000) Chronic idiopathic inflammatory bowel diseases of the horse. J Vet Intern Med 14, 258-265 PubMed.
  • Southwood L et al (2000) Idiopathic focal eosinophilic enteritis associated with small intestinal obstruction in 6 horses. Vet Surg 29, 415-419 PubMed.
  • Scott E et al (1999) Inflammatory bowel disease in horses: 11 cases (1988-1998). JAVMA 214 (10), 1527-1530 PubMed.
  • Nimmo Wilkie J et al (1985) Chronic eosinophilic dermatitis: a manifestation of a multisystemic eosinophilic, epitheliotropic disease in five horses. Vet Pathol 22, 297-305 PubMed.

Other sources of information

  • Roberts M (2004) Proliferative and inflammatory intestinal diseases associated with malabsorption and maldigestion. In: Equine Internal Medicine. Eds: Reed S, Bayly W M & Sellon D C. 2nd edn. Saunders, USA. pp 878-884.

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