Gastrointestinal aspergillosis and zygomycosis of cattle.

Gastrointestinal mycosis was diagnosed in 73 lesions of 32 cattle without a history of engorgement, and tissues of 29 animals were examined histopathologically. The omasum was the target organ for infection, followed by the rumen and reticulum. Acute necrohemorrhagic lesions dominated, with infiltration of neutrophils and thrombosis. The etiologic diagnosis was accomplished by indirect immunohistochemical staining of fungal elements with a panel of mono- and polyclonal antibodies raised against fungal antigens. Aspergillosis and zygomycosis were diagnosed in one or more organs of 11 (34.4%) and 20 (62.5%) cattle, respectively, and dual infections were found in three lesions of two animals. Candidosis was diagnosed in only one case. Hematogenous spread of fungi predominantly to the liver was seen in nine animals. Lymphogenic spread of aspergilli to mesenteric and omasal lymph nodes occurred in one and two animals, respectively. Factors that seemed to predispose to mycotic infection included presence of other diseases and intense antimicrobial therapy. These factors and post-partum status, which included 23 of 29 (79.3%) cows, predisposed to mycosis in several ways, e.g., reflux of acidic abomasal contents into the forestomachs, stasis of proventricular content, metabolic dysfunctions, and stress.