FieldDxMultisystemic, eosinophilic, epitheliotropic diseaseClinical signs, differential diagnosis, treatment and prevention in horses.
Overview
A rare, serious multi-organ disease of adult horses. Unknown; an abnormal eosinophil-driven inflammatory process is suspected, but the underlying trigger has not been identified.
Clinical signs
- Characterized by the infiltration of eosinophils into a wide range of tissues.
- Clinical signs include: (a) Cutaneous: Pale mucous membranes, skin lesions with alopecia, hyperkeratosis, and lichenification; lesions of the coronary band and mouth are common; urticaria occurs.
- (b) Respiratory: Eosinophilic interstitial pneumonia or pulmonary diffuse granulomas, which can result in veno-occlusive remodeling and epistaxis.
- (c) Systemic: Hepatic diffuse granulomas, weight loss, and eosinophilic meningoencephalitis.
Predisposing factors
- The precise etiology is unknown (idiopathic in most horses).
- Some cases are associated with lymphosarcoma or increased numbers of CD3-positive cells, suggesting clonal expansion of a T-lymphocyte population that secretes interleukin-5.
Look-alikes to rule out
Treatment
- No consistently effective treatment exists and the long-term prognosis is poor; MEED responds poorly to therapy.
- Immunosuppressive doses of corticosteroids are the mainstay — dexamethasone (reported at approximately 0.05–0.1 mg/kg IV or IM daily, then tapered) or prednisolone (1–2 mg/kg PO daily, tapered to alternate-day dosing).
- Hydroxyurea has been used in combination with corticosteroids in individual cases with partial improvement.
- Supportive and nutritional therapy: highly digestible, low-residue, high-quality feed offered in small frequent meals; parenteral nutrition if malabsorption is severe.
- Larvicidal anthelmintic treatment and dietary change are often trialled because an aberrant response to parasitic or dietary antigens is suspected.
- Topical and systemic care of exfoliative skin and coronary-band lesions; treat secondary bacterial infection.
Drugs mentioned: Dexamethasone Prednisolone Hydroxyurea
Prevention
1. No specific preventive measures are established, because the cause is unknown (idiopathic in most horses) and cases are rare and sporadic. 2. General recommendations aimed at the suspected antigenic triggers: maintain a consistent, good-quality diet and avoid abrupt dietary change; minimise exposure to inhaled dusts and moulds. 3.
Source
The Merck Veterinary Manual 11th Edition (Page 1000) 109, 110. Cols G, H added from: Merck Veterinary Manual, "Inflammatory Bowel Disease in Horses" (MEED is classified here), https://www.merckvetmanual.com/digestive-system/miscellaneous-intestinal-diseases-in-horses/inflammatory-bowel-disease-in-horses
MSD Veterinary Manual — Multisystemic Eosinophilic Epitheliotropic Disease (accessed 2026-08-11)
Condensed and attributed, never reproduced whole. Open the full entry in the app.