Enteritis, Eosinophilic

Histology of Eosinophilic enteritis in the horse ^{©Susan Rhind, University of Edinburgh}

Introduction

Eosinophilic enteritis (EE) is the second most common form of IBD, characterised by a mixed, but predominantly eosiphilic, mucosal inflammatory infiltration. EGE may be limited to the small intestine or it may affect other areas of the gastrointestinal tract such as stomach or colon; the condition is cetegorised into focal or diffuse EE.

An eosinophilic infiltrate may indicate a diet-induced, type 1 hypersensitivity. However, most dogs do not respond to a purely exclusion diet. Endoparasitism should also be excluded prior to immunosuppressive therapy for EE.

Signalment

Focal EE is a disease of young dogs, which can be associated with Toxocara canis infection. Pin-head sized white nodules can be seen under the serosa in the bowel, consisting of eosinophils, and occasionally macrophages, plasma cells and Toxocara larvae.

The diffuse form of EE is seen in the dog, cat and horse; it is described as idiopathic but the aetiology has been suggested to be a hypersensitivity reaction. In this form of the condition, recurrent episodes of diarrhoea with tissue and circulatory eosinophilia occurs, with a heavy infiltrate of eosinophils present histologically in all layers of the stomach and intestines.

There is a predilection for diffuse EE in:

• Boxers
• Dobermans
• German Shepherd Dogs

Clinical Signs

• Vomiting
• Diarrhoea; small intestinal is more common with haematoemesis or malena, and/or haematochezia; EGE is associated with mucosal erosion or ulceration
• Protein-losing enteropathy in severe cases
• Hypoproteinaemia in severe cases

Laboratory Tests

Haemotology reveals an anaemia if gastrointestinal haemorrhage is severe. Eosinophilia is not always present and even when seen it is not pathogneumonic for EE. Panhypoproteinaemia can be found secoondary to concurrent protein-losing enteropathy

Diagnostic Imaging

Endoscopically, linear ulcers within the duodenal mucosa may be seen grossly.

Histopathology

Biopsy is required for a definitive diagnosis.

Treatment

Anti-parasiticide (Fenbendazole) treatment may be given due to the possible endoparasitism or dietary sensitivity. Dietary modification is required with a chamge to a hypoallergenic diet. Immunosuppressive therapy may also be required.

Prognosis

Guarded if the initial response to treatment is poor. Good if the underlying cause is detected and successfully treated.

References

• Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
• Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA
• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.