Chronic copper toxicity in a dairy cow.

A three year old Holstein dairy cow fed a ration containing a copper supplement died of chronic copper poisoning. The concentration of copper in the liver was 331 ppm (wet weight). The typical lesions of chronic copper toxicity including icterus, hepatic fibrosis and hemoglobinemic nephrosis were found at necropsy. The chronic copper toxicity was not considered to be a herd problem since the liver copper concentration in a slaughtered cull animal and blood samples taken from five animals in the same herd were within normal limits.