Invasive Pulmonary Aspergillosis of Horses: An Association with Acute Enteritis

Invasive pulmonary aspergillosis was identified in 19 horses. In 16 cases mycotic lesions were associated with enterocolitis; 14 cases appeared to result from Salmonella infection. Pulmonary lesions included multifocal areas of acute necrosis, leukocytoclastic vasculitis, and thrombosis with fibrinosuppurative inflammation surrounding mycelial masses. Thromboemboli with fungi were in the brain and kidneys of three cases. Factors which appeared to predispose to pulmonary aspergillosis included corticosteroid therapy, disseminated neoplasms, hepatitis, pleuritis, and peritonitis. This study suggests that immunocompromise and invasion of Aspergillus sp. from damaged intestine are more important in causing equine pulmonary aspergillosis than inhalation of spores.