Severe pulmonary disease due to multisystemic eosinophilic epitheliotropic disease in a horse.
Authors: Singh K, Holbrook T C, Gilliam L L, Cruz R J, Duffy J, Confer A W
Journal: Veterinary pathology
Summary
# Editorial Summary A 17-year-old Quarter Horse mare with progressive respiratory distress was found at necropsy to have multisystemic eosinophilic epitheliotropic disease—a rare, idiopathic condition characterised by fibrosing eosinophilic granulomas affecting multiple organ systems. The lungs were severely affected with innumerable discrete nodules distributed in a miliary pattern throughout the pulmonary parenchyma, whilst similar lesions were identified in the liver and renal lymph nodes, confirmed through histological examination and exclusion of infectious or parasitic aetiologies. This case is noteworthy because chronic respiratory disease in older horses rarely stems from eosinophilic granulomatous disease, making it an important differential diagnosis to consider when conventional investigations fail to identify a causative agent. Clinicians managing horses presenting with insidious, progressive dyspnoea unresponsive to standard respiratory protocols should factor idiopathic multisystemic eosinophilic disease into their diagnostic algorithm, though definitive diagnosis requires histopathological evaluation. The prognosis appears grave given the extensive parenchymal involvement and systemic distribution documented in this case, highlighting the need for early recognition and further investigation into potential aetiologies and treatment options for this poorly understood condition.
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Practical Takeaways
- •Multisystemic eosinophilic epitheliotropic disease should be considered as a differential diagnosis in horses with chronic respiratory distress and pulmonary nodules that do not respond to conventional treatment
- •The diagnosis requires histologic examination showing fibrosing eosinophilic granulomas; imaging alone cannot differentiate this condition from other causes of miliary lung disease
- •This is a rare, serious condition with poor prognosis; recognition is important for accurate case documentation and understanding disease prevalence in the equine population
Key Findings
- •A 17-year-old Quarter Horse mare presented with chronic respiratory distress caused by multisystemic eosinophilic epitheliotropic disease
- •Necropsy revealed innumerable discrete spherical nodules in miliary pattern throughout pulmonary parenchyma with fibrosing eosinophilic granulomas on histology
- •Lesions were multisystemic with similar nodules scattered in liver and renal lymph nodes, with no identifiable etiologic agent