section name header

Basics ⬇

Outline

BASICS

Eosinophilic enteritis presents in 2 main forms—either acute, focal or chronic diffuse. In some cases there may be some overlap of these forms.

Acute, Focal!!navigator!!

Definition

  • These lesions are most frequently termed idiopathic focal eosinophilic enteritis and are characterized by 1 or more hyperemic, palpably thickened, circumferential or antimesenteric plaque-like lesions
  • Variably termed inflammatory bowel disease, idiopathic eosinophilic enteritis, multifocal eosinophilic enteritis, and circumferential mural bands
  • Impaction of ingesta can develop oral to a lesion, resulting in simple obstruction of the SI and acute colic. This is due to a reduction in luminal diameter at the site and localized ileus due to inflammation
  • It can be difficult to establish a diagnosis without confirmation at laparotomy enabling other causes of SI obstruction to be ruled out
  • Surgical management is required to decompress the SI and prevent gastric overload and sometimes rupture. Ongoing SI distention can result in venous occlusion and ischemia of distended SI proximal to the impaction and secondary SI volvulus can develop
  • Relatively rare cause of SI obstruction. More frequent in certain geographic regions including parts of the USA, Ireland, and the UK; subjective increase in prevalence in northwest UK in the last 10–15 years

Signalment

Younger horses at greatest risk but can occur in any age.

Signs

Acute abdominal pain consistent with nonstrangulating obstruction of the SI.

Causes

  • Unknown, speculated to be an acute inflammatory response to an antigen. There is no evidence that high parasite burdens are a cause. Lesions do not recur, so the cause appears to be different than the chronic, diffuse form
  • Age and fall months in specific geographic regions are key risk factors

Risk Factors

See Causes.

Chronic Diffuse!!navigator!!

Definition

  • Diffuse infiltration of the SI mucosa with eosinophils and lymphocytes
  • This is a subgroup of IBD lesions that may occur in the horse
  • Eosinophil infiltration may affect other regions of the intestinal tract, including the large colon and other organs such as the skin and liver (MEED)

Pathophysiology

Inflammation and cell infiltration in the gut wall result in protein-losing enteropathy and SI malabsorption.

Systems Affected

Eosinophil infiltration may be confined to the SI and other areas of the intestinal tract, and in horses with MEED may involve the skin, liver, pancreas, esophagus, oral cavity, lungs, and mesenteric lymph nodes.

Genetics

N/A

Incidence/Prevalence

The true prevalence is unknown.

Geographic Distribution

Reported in multiple countries.

Signalment

Young horses (up to 4 years of age) are reported to be more commonly affected, as are Standardbred and Thoroughbred horses.

Signs

  • Recurrent colic
  • Weight loss
  • Diarrhea (if infiltration of the large colon)
  • In horses with MEED other clinical signs may be evident dependent on the organ affected, e.g. severe dermatitis in horses with extensive eosinophil infiltration in the skin

Causes

Unknown. A type 1 hypersensitivity reaction to an unknown antigen is suspected. Dietary, inhaled, or parasitic antigens have been proposed.

Diagnosis ⬆ ⬇

Outline

DIAGNOSIS

Acute, Focal!!navigator!!

Differential Diagnosis

Other forms of nonstrangulating SI obstructions, e.g. ileal impaction, anterior enteritis.

CBC/Biochemistry/Urinalysis, Other Laboratory Tests

There are no key diagnostic tests characteristic of idiopathic focal eosinophilic enteritis—these are largely dependent on duration of SI obstruction and degree of systemic compromise.

Imaging

  • Distention of SI confirmed using transabdominal ultrasonography. The intestinal wall is of normal thickness, but if lesions are visualized there is localized mural thickening
  • Excess peritoneal fluid may be evident

Other Diagnostic Procedures

  • Nasogastric intubation—net reflux of >2 L may be obtained depending on duration of SI obstruction and location of the obstruction in the SI
  • Rectal examination—distended SI may be palpated
  • Abdominocentesis—total protein, lactate, and white blood cells are usually within normal range (consistent with a nonstrangulating SI obstruction). Eosinophils may or may not be seen on cytologic examination of the fluid
  • Exploratory laparotomy—the only way in which the cause of SI obstruction can be confirmed and other causes of SI obstruction ruled out. Lesions may be single but up to over 40 separate lesions may be evident

Pathologic Findings

Visual appearance of gross lesions and confirmation on histopathology.

Chronic, Diffuse!!navigator!!

Differential Diagnosis

  • Other forms of IBD, e.g. granulomatous enteritis, lymphocytic/plasmacytic enteritis, intestinal lymphosarcoma, infectious causes (Lawsonia intracellularis, Rhodococcus equi) in foals/weanlings
  • Other causes of recurrent colic

CBC/Biochemistry/Urinalysis

  • CBC—peripheral eosinophilia uncommon, may be normal or neutrophilia evident; hyperfibrinogenemia, anemia
  • Biochemistry—hypoproteinemia due to hypoalbuminemia, globulins variable. In horses with MEED other abnormalities may be seen, e.g. elevated γ-glutamyltransferase if eosinophilic infiltration of the liver
  • Urinalysis—rule out proteinuria

Other Laboratory Tests

N/A

Imaging

Abdominal ultrasonography—transcutaneous and per rectum. Identification of thickened SI wall (>3–5 mm thickness). Imaging of both sides of the abdomen to evaluate other areas of the gastrointestinal tract and other organs.

Other Diagnostic Procedures

  • Abdominocentesis—to rule out neoplastic causes of SI disease, peritonitis. Increased eosinophils may be seen on cytology
  • Duodenal biopsy (gastroscopy)—may not be helpful if this portion of the SI is not affected and also because full-thickness biopsies are required
  • Rectal biopsy—may assist diagnosis
  • Absorption tests—oral glucose or d-xylose absorption tests, results may be normal in horses with eosinophilic enteritis unlike other forms of IBD
  • SI biopsy—definitive diagnosis. Multiple, full-thickness biopsies including visibly normal and abnormal intestine required. Usually performed by conventional laparotomy to inspect other areas of the gastrointestinal tract and obtain biopsies from the large colon but a standing flank laparotomy can be performed in horses with severe systemic compromise (general anesthesia considered too risky)
  • Parasite testing—determine intestinal parasite burden

Pathologic Findings

Confirmation of diagnosis on histopathologic examination of tissues.

Treatment ⬆ ⬇

Outline

TREATMENT

Acute, Focal!!navigator!!

  • Exploratory laparotomy to confirm the diagnosis, rule out other causes of SI obstruction, and to decompress SI
  • Surgical resection of lesions is not required, unless there is marked compromise of the SI lumen due to stricture formation

Chronic, Diffuse!!navigator!!

Appropriate Health Care

Rule out other causes of weight loss/failure to gain weight/recurrent colic, e.g. diet, dental disease.

Nursing Care

N/A

Activity

N/A

Diet

Dietary allergens have been proposed as a potential cause so dietary modification may be trialed. There is no evidence as to a specific diet that may be recommended. Oil may added to the diet—additional fat and calories.

Surgical Considerations

N/A

Medications ⬆ ⬇

Outline

MEDICATIONS

Acute, Focal!!navigator!!

  • IV fluid therapy with isotonic fluids—depending on the degree of preoperative systemic compromise and development of POI/POR
  • Flunixin meglumine 1.1 mg/kg IV every 12 h
  • Antimicrobials as per clinic protocol following laparotomy
  • IV 0.1 mg/kg dexamethasone may be given IV during surgery to reduce the inflammatory reaction. No evidence about optimal dose and duration, ongoing steroid therapy not normally recommended to avoid impaired healing of the laparotomy incision
  • Prokinetic therapy if POR develops

Chronic, Diffuse!!navigator!!

Drug(s) of Choice

  • Steroid therapy—little evidence regarding the optimal dose and duration of administration
  • Parenteral administration recommended initially (3 days to 3 weeks) with 0.05–0.1 mg/kg dexamethasone IM/IV followed by a tapering course of oral prednisolone or dexamethasone
  • Ongoing medication may be required—response to treatment and relapse of clinical signs following reduction/cessation of steroid therapy
  • Anthelmintics administered as required

Contraindications

N/A

Precautions

Complications associated with prolonged corticosteroid use.

Possible Interactions

N/A

Alternative Drugs

N/A

Follow-up ⬆ ⬇

Outline

FOLLOW-UP

Acute, Focal!!navigator!!

  • The chronic dilation of the SI may result in venous occlusion of SI proximal to the site of obstruction, which may result in ischemia–reperfusion injury and development of POR
  • Frequent nasogastric decompression required if POR develops to prevent gastric rupture
  • Reobstruction of ingesta at lesions may occur in the early postoperative period (colic signs and development of nasogastric reflux), and care should be taken to reintroduce feed gradually, particularly in the first 7 days
  • Lesions appear to resolve within 3–7 days and recurrence has not been documented. Ongoing medical therapy is not required
  • Long-term survival is good provided complications do not occur in the early postoperative stage with rates of up to 100% reported

Chronic, Diffuse!!navigator!!

Patient Monitoring

Ongoing monitoring of clinical progress and assessment of weight gain/reduction in colic episodes.

Prevention/Avoidance

N/A

Possible Complications

N/A

Expected Course and Prognosis

The prognosis is generally considered to be poor, some reports of successful management of chronic, diffuse eosinophilic enteritis.

Miscellaneous ⬆ ⬇

Outline

MISCELLANEOUS

Synonyms!!navigator!!

Inflammatory bowel disease

Abbreviations!!navigator!!

  • IBD = inflammatory bowel disease
  • MEED = multisystemic eosinophilic epitheliotropic disease
  • POI = postoperative ileus
  • POR = postoperative reflux
  • SI = small intestine

Suggested Reading ⬆ ⬇

Archer DC, Edwards GB, Kelly DF, et al. Obstruction of equine small intestine associated with focal idiopathic eosinophilic enteritis: an emerging disease? Vet J 2006;171:503–512.

Archer DC, Costain DA, Sherlock C. Idiopathic focal eosinophilic enteritis (IFEE), an emerging cause of abdominal pain in horses: the effect of age, time and geographical location on risk. PLoS One 2014;9(12):e112072.

Kalck KA. Inflammatory bowel disease in horses. Vet Clin North Am Equine Pract 2009;25:303–315.

Perez Olmos JF, Schofield WF, Dillon H, et al. Circumferential mural bands in the small intestine causing simple obstructive colic: a case series. Equine Vet J 2006;38:354–349.

Schumacher J, Edwards JF, Cohen ND. Chronic idiopathic inflammatory bowel diseases of the horse. J Vet Intern Med 2000;14:258–265.

Southwood LL, Kawcak CE, Trotter GW, et al. Idiopathic focal eosinophilic enteritis associated with small intestinal obstruction in 6 horses. Vet Surg 2000;29:415–419.

Author(s) ⬆

Author: Debra C. Archer

Consulting Editors: Henry R. Stämpfli and Olimpo Oliver-Espinosa