Equine multinodular pulmonary fibrosisClinical signs, differential diagnosis, treatment and prevention in horses.

• Progressive fibrosing lung disease.
• Clinical signs include weight loss, recurrent cough, depression, anorexia, fever, tachycardia, tachypnea, or respiratory distress.
• There is systemic evidence of inflammation, and exercise tolerance is severely diminished.
• High case-fatality rate (>50% in both treated and untreated horses).
• Radiographic examination shows severe, diffuse interstitial disease with nodular opacities.
• Ultrasonography demonstrates multiple nodules in the lung parenchyma confluent with the pleural surface (no excess pleural fluid is present).
• CBC reveals neutrophilic leukocytosis, mild anemia, lymphopenia, hyperfibrinogenemia, hypoproteinemia, and hypoalbuminemia.
• Macrophages in tracheal aspirate contain occasional intranuclear inclusions.

• Strongly associated with equine herpesvirus-5 (EHV-5) infection (a gamma-herpesvirus), where EHV-5 is detected in lung lesions or bronchoalveolar lavage fluid.
• Pulmonary or bone marrow lymphoma may be associated with the virus.

Recurrent Airway Obstruction

• Not fully established as there is no specific treatment.
• Corticosteroids (e.g., dexamethasone or prednisolone) and antiviral drugs (such as acyclovir) have been administered.
• Treatment of secondary infections is indicated.
• Percutaneous lung biopsy may carry risks in dyspneic horses.

Drugs mentioned: Dexamethasone Prednisolone Acyclovir

A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs and Goat by ELSEVIER (Pages 482–488) 97, 98, 100-102, 105, 106; The Merck Veterinary Manual 11th Edition (Pages 883–884) 99, 103.

MSD Veterinary Manual — Equine multinodular pulmonary fibrosis and lymphoma (accessed 2026-08-11)

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