Equine multisystemic eosinophilic epitheliotropic disease: a case report and review of literature.

This research presents a case study of a 2-year-old horse suffering from multisystemic eosinophilic epitheliotropic disease (MEED), a rare and typically chronic condition. The study outlines the horse’s symptoms, the progression of the disease, and the diagnostic process, ultimately culminating in the horse’s euthanization due to its poor prognosis.

Clinical Presentation

• The horse was brought in with a one-week history of fever, lack of appetite, and skin lesions. These lesions were causing severe itchiness and swelling, and were unaffected by prior therapies.
• The horse was in poor physical condition, with diffused hair loss, lethargy, and skin crusting.
• Over time, its temperature rose up to 40°C. Ten days after beginning treatment, the horse developed severe diarrhea and worsening skin lesions.

Diagnostic Findings

• Skin biopsies revealed lymphoplasmacytic and eosinophilic dermatitis, which represents inflammation of the skin caused by immune cell infiltration.
• Ulcerative gastritis, inflammation of the intestines, severe subcutaneous swelling, and the thickening of the bile ducts were some other notable findings.
• Upon examining the tissues from various key organs such as the skin, gastrointestinal tract, lymph nodes, bile ducts, pancreatic duct, and kidney, a significant presence of eosinophils and lymphoplasmacytic cells was found. These types of cells are generally associated with inflammation and allergic reactions.
• Immunohistochemistry, a process that visualizes proteins in cells of a tissue section, showed a clear predominance of CD3-positive cells in lymphocyte infiltrations. This type of cell is a marker of T cell infiltration, indicating immune system over-activity.

Diagnosis and Conclusions

• Based on the clinical findings and the results of the histopathology examination, a diagnosis of Multisystemic Eosinophilic Epitheliotropic Disease (MEED) was made.
• MEED is an uncommon condition in horses that is usually chronic. However, in this case, the horse showed an apparently acute onset with high fever and rapid clinical deterioration.
• The study suggests that MEED should be considered in horses presenting with weight loss and skin lesions, with or without fever, and that the definitive diagnosis is based on histological analysis of biopsy specimens from affected organs.