Suspected infectious necrotic hepatitis (black disease) in Oregon cattle.

Suspected infectious necrotic hepatitis (black disease) in a herd of 436 cattle in Douglas County, Oregon, resulted in 79 deaths during a 2-week period. Although Clostridium novyi could not be isolated from hepatic lesions, the clinical course of the disease, gross and histopathologic findings, and fluorescent antibody identification of C novyi in various tissues were suggestive of the disease. The epizootic was preceded by a long drought, during which grazing conditions were sparse. A few days before the 1st dead animal was found, the drought was relieved by about 10 cm (4 in) of rainfall, resulting in the growth of young succulent grass. The cattle, attempting to eat this new grass lying close to the ground, consumed large quantities of soil. It was speculated that the soil contained C novyi and that the proliferation of these ingested organisms in necrotic tissue cuased by Fasciola hepatica resulted in fatal toxemia.