Equis ISSN 2398-2977

Intestine: enteritis - granulomatous

Contributor(s): Prof Jonathon Naylor, Vetstream Ltd


  • Cause: form of inflammatory bowel disease (IBD) similar to Chron's disease in humans. Malabsorptive and maldigestive condition most commonly affecting the small intestine, although the large intestine can be affected in advanced cases. Unknown cause, althoughMycobacterium aviumhas been implicated in a few cases and familial predisposition is suspected in Standardbred horses   Standardbred  .
  • Signs: insidious or rapid weight loss, poor condition, lethargy, dependent edema, +/- diarrhea, intermittent colic   Abdomen: pain - adult  and alopecia. Demeanor can remain bright with good appetite or anorexia may be reported.
  • Diagnosis: gastrointestinal evaluation   Gastrointestinal: physical examination  , including rectal palpation   Urogenital: rectal palpation  (enlarged mesenteric lymph nodes, thickened small intestinal wall   Duodenum: transmural thickening - ultrasound  ), abdominal ultrasound, duodenal and rectal biopsies; granulomatous enteritis confirmed by histopathology of affected intestine (diffuse and patchy infiltrates, distinct granulomas, with epithelioid, lymphoid and giant cells, macrophages; lymphoid hyperplasia, perilymphatic and transmural inflammation, lymphangiectasia, villous atrophy, mucosal ulceration, fibrosis, crypt abscesses, serosal fibrosis).
  • Treatment: dietary management and corticosteroids are the treatment of choice, with prolonged courses of treatment necessary.
  • Prognosis: generally poor, due to advanced nature of disease at the time of diagnosis.



  • Possible abnormal host inflammatory response to intestinal bacteria or dietary components.
  • Acid-fast bacteria may have been found in the intestinal tissue of some horses affected by granulomatous enteritis.Mycobacterium aviumwas identified in the majority of these cases.
  • Possible role forMycobacterium pseudotuberculosis(similar to Johne's disease in cattle).



  • Thought to be similar Crohn's disease in humans, whereby activation of mucosal T cells leads to transmural inflammation. This is amplified and perpetuated by pro-inflammatory cytokines.


  • Often advanced at time of diagnosis.


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Further Reading


Refereed papers

  • Recent references fromPubMed andVetMedResource.
  • Kalck K A (2009)Inflammatory bowel disease in horses.Vet Clin North Am Equine Pract 25(2), 303-315PubMed.
  • Mair T S, Pearson G R & Divers T S (2006)Malabsorption syndromes in the horse.Equine Vet Educ18(6), 299-308VetMedResource.
  • Swain J M, Licka T, Rhind S M & Hudson N P (2003)Multifocal eosinophilic enteritis associated with a small intestinal obstruction in a standardbred horse.Vet Rec24(152), 648-651PubMed.
  • Schumacher J, Edwards J F & Cohen N D. (2000)Chronic idiopathic inflammatory bowel diseases of the horse.J Vet Intern Med14(3), 258-265PubMed.
  • Fogarty Uet al(1998)A cluster of equine granulomatous enteritis cases, the link with aluminum.Vet Hum Toxicol40(5), 297-305VetMedResource.
  • Duryea J Het al(1997)Clinical remission of granulomatous enteritis in a standardbred gelding following long-term dexamethasone administration.Equine Vet J29(2), 164-167PubMed.
  • Lindberg Ret al(1996)Rectal biopsy diagnosis in horses with clinical signs of intestinal disorders, a retrospective study of 116 cases.Equine Vet J28(4), 275-284PubMed.
  • Woods P Ret al(1993)Granulomatous enteritis and cutaneous arteritis in a horse.JAVMA203(11), 1573-1575PubMed.
  • Johnson P Jet al(1993)Granulomatous enteritis and Campylobacter bacteremia in a horse.JAVMA203(7), 1039-1042PubMed.
  • Mair T S, Hillyer M H, Taylor F G R & Pearson G R (1991)Small intestinal malabsorption in the horse: an assessment of the specificity of the oral glucose tolerance test.Equine Vet J23(5), 344-346PubMed.
  • Schumacher Jet al(1990)Effect of intestinal resection on two juvenile horses with granulomatous enteritis.J Vet Intern Med4(3), 153-156PubMed.
  • Cooley A Jet al(1987)Molluscum contagiosum in a horse with granulomatous enteritis.J Comp Pathol97(1), 29-34PubMed.
  • Platt Het al(1986)Chronic inflammatory and lymphoproliferative lesions of the equine small intestine.J Comp Pathol96(6), 671-684PubMed.
  • Sweeney R Wet al(1986)Chronic granulomatous bowel disease in three sibling horses.JAVMA188(10), 1192-1194PubMed.
  • Lindberg Ret al(1986)Ultrastructure of granulomatous infiltrates in the small bowel in equine granulomatous enteritis.Zentralbl Veterinarmed (A)33(2), 111-122PubMed.
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  • Lindberg Ret al(1984)Pathology of equine granulomatous enteritis.J Comp Pathol94(2), 233-247PubMed.
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  • Bester R Cet al(1978)A chronic wasting syndrome in a horse associated with granulomatous enteritis.J S Afr Vet Assoc49(4), 351-353PubMed.
  • Merritt A Met al(1976)Granulomatous enteritis in nine horses.JAVMA169(6), 603-609PubMed.
  • Merritt A Met al(1975)Differential diagnosis of diarrhea in horses over six months of age.J S Afr Vet Assoc46(1), 73-76PubMed.
  • Cimprich R Eet al(1974)Equine granulomatous enteritis.Vet Pathol11(6), 535-547PubMed.