Polioencephalomalacia and photosensitization associated with Kochia scoparia consumption in range cattle.

Cattle consuming only Kochia scoparia in a pasture southeastern Colorado became ill. Clinical signs were lacrimation, depression, anorexia, nystagmus, head pressing, and recumbency. Some cattle died acutely, with the only clinical signs being recumbency, nystagmus, and occasionally opisthotonos. Pathologic findings were pulmonary edema and congestion, hepatic necrosis and fibrosis, necrosis of proximal convoluted tubular epithelium in the kidneys, epidermal necrosis of lightly pigmented areas, and laminar cerebrocortical necrosis. When the cattle were removed from the pasture, the problem ceased.