Equine pulmonary mycosis due to Aspergillus niger and Rhizopus stolonifer

Invasive pulmonary mycosis caused by Aspergillus niger and Rhizopus stolonifer is reported in a 2-year-old horse, one of three that died after being housed in a disused, uncleaned stable. Lesions were characterized by thrombosis of the blood vessels with haemorrhage and tissue necrosis. Fungal hyphae were observed both in thrombosed vessels and in adjacent necrotic tissue. In culture media inoculated with lung samples and samples from the bedding hay, two types of colony were recorded and identified as A. niger and R. stolonifer. This study is the first description of equine pulmonary mucormycosis and of A. niger as an aetiological agent in the horse.