Idiopathic focal eosinophilic enteritis

From Horse
Linear lesion associated with acute IFEE
Well-circumscribed linear lesion associated with IFEE

Idiopathic focal eosinophilic enteritis (IFEE) and diffuse eosinophilic enteritis (DEE) (forms of inflammatory bowel disease) are primary eosinophilic intestinal conditions without a known cause that are associated with an increasing number of surgical colic cases in horses.

The involvement of inflammatory eosinophils suggests either and immune-mediated or parasitic cause of the disease, but none has as yet been proven[1].


IFEE lesions represent an accumulation of leucocytes in submucosa and muscularis, with dominance of eosinophils and macrophages and small numbers of lymphocytes, plasma cells and neutrophils. T cells represent the dominant lymphocytes. Macrophages are often significantly more prevalent in the mucosal and submucosal infiltrates in IFEE nonlesion sites than in DEE, and lymphocytes significantly more prevalent in the mucosa in DEE than in IFEE nonlesion sites.

IFEE is a primary eosinophilic intestinal disorder characterised by a focally exacerbated inflammatory reaction in horses with DEE, possibly due to functional changes in the macrophage and T cell components, with subsequent excessive recruitment of both eosinophils and macrophages[2].

Clinical signs

Clinical signs of IFEE are non-specific and can range from anorexia to intermittent colic. Most cases worsen with time, necessitating surgical intervention[3].

It is characterised by focal or diffuse eosinophilic infiltration of the gastrointestinal tract, and is usually associated with dyspepsia, diarrhea and peripheral eosinophilia. Diffuse gastrointestinal tract and colonic involvement are uncommon. The endoscopic appearance may vary from normal to mucosal nodularity and ulceration. Gastrointestinal obstruction is unusual and is associated with predominantly muscular disease.


Diagnosis of IFEE is usually made by laparotomy and confirmed by histological examination of resected abnormal small intestine. Most cases are associated with jejunal obstruction involving visibly striking and palpably thickened serosal plaques or circumferential constrictions.


Where severe signs of pain are seen in affected horses, surgery is necessary to enable the impaction to be cleared. The lesions on the intestine are very distinctive appearing as red bands that seem to wrap around the circumference of the intestine or more focal plaque like thickenings.

Although the cause of these focal eosinophilic enteritis lesions is unknown, the long-term outcome after lesion resection is favorable after lesion resection.


  1. Archer, DC et al (2006) Obstruction of equine small intestine associated with focal idiopathic eosinophilic enteritis: An emerging disease? Veterinary Journal 171(3):504-512
  2. Makinen, PE (2008) Characterisation of the inflammatory reaction in equine idiopathic focal eosinophilic enteritis and diffuse eosinophilic enteritis. Equine Vet J 40(4):386-392
  3. Southwood, LL et al (2000) Idiopathic focal eosinophilic enteritis associated with small intestinal obstruction in 6 horses. Vet Surg 29:415-419