ISSN 2398-2977      

Intestine: enteritis - granulomatous



  • 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 from PubMed and VetMedResource.
  • Kalck K A (2009) Inflammatory bowel disease in horses. Vet Clin North Am Equine Pract 25 (2), 303-315 PubMed.
  • Mair T S, Pearson G R & Divers T S (2006) Malabsorption syndromes in the horse. Equine Vet Educ 18 (6), 299-308 VetMedResource.
  • 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 Rec 24 (152), 648-651 PubMed.
  • Schumacher J, Edwards J F & Cohen N D (2000) Chronic idiopathic inflammatory bowel diseases of the horse. J Vet Intern Med 14 (3), 258-265 PubMed.
  • Fogarty U et al (1998) A cluster of equine granulomatous enteritis cases, the link with aluminum. Vet Hum Toxicol 40 (5), 297-305 VetMedResource.
  • Duryea J H et al (1997) Clinical remission of granulomatous enteritis in a standardbred gelding following long-term dexamethasone administration. Equine Vet J 29 (2), 164-167 PubMed.
  • Lindberg R et al (1996) Rectal biopsy diagnosis in horses with clinical signs of intestinal disorders, a retrospective study of 116 cases. Equine Vet J 28 (4), 275-284 PubMed.
  • Woods P R et al (1993) Granulomatous enteritis and cutaneous arteritis in a horse. JAVMA 203 (11), 1573-1575 PubMed.
  • Johnson P J et al (1993) Granulomatous enteritis and Campylobacter bacteremia in a horse. JAVMA 203 (7), 1039-1042 PubMed.
  • 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 J 23 (5), 344-346 PubMed.
  • Schumacher J et al (1990) Effect of intestinal resection on two juvenile horses with granulomatous enteritis. J Vet Intern Med (3), 153-156 PubMed.
  • Cooley A J et al (1987) Molluscum contagiosum in a horse with granulomatous enteritis. J Comp Pathol 97 (1), 29-34 PubMed.
  • Platt H et al (1986) Chronic inflammatory and lymphoproliferative lesions of the equine small intestine. J Comp Pathol 96 (6), 671-684 PubMed.
  • Sweeney R W et al (1986) Chronic granulomatous bowel disease in three sibling horses. JAVMA 188 (10), 1192-1194 PubMed.
  • Lindberg R et al (1986) Ultrastructure of granulomatous infiltrates in the small bowel in equine granulomatous enteritis. Zentralbl Veterinarmed (A) 33 (2), 111-122 PubMed.
  • Lindberg R et al (1985) Clinical and pathophysiologic features of granulomatous enteritis and eosinophilic granulomatosis. Zentralbl Veterinarmed (A) 32 (7), 536-539 VetMedResource.
  • Lindberg R et al (1985) Topography and enterocyte morphology of the small bowel mucosal surface in equine granulomatous enteritis. J Comp Pathol 95 (1), 65-78 PubMed.
  • Lindberg R et al (1984) Pathology of equine granulomatous enteritis. J Comp Pathol 94 (2), 233-247 PubMed.
  • Roberts M C et al (1980) Granulomatous enteritis in a young Standardbred mare. Aust Vet J 56 (5), 230-233 PubMed.
  • Bester R C et al (1978) A chronic wasting syndrome in a horse associated with granulomatous enteritis. J S Afr Vet Assoc 49 (4), 351-353 PubMed.
  • Merritt A M et al (1976) Granulomatous enteritis in nine horses. JAVMA 169 (6), 603-609 PubMed.
  • Merritt A M et al (1975) Differential diagnosis of diarrhea in horses over six months of age. J S Afr Vet Assoc 46 (1), 73-76 PubMed.
  • Cimprich R E et al (1974) Equine granulomatous enteritis. Vet Pathol 11 (6), 535-547 PubMed.

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