Susceptibility of North Ronaldsay sheep to copper from cupric oxide needles.

Three housed North Ronaldsay sheep were treated with copper in the form of cupric oxide "needles", two at the manufacturer's recommended dosage rate and the third at twice this level. Sheep of this breed are especially sensitive to high dietary intake of copper. Pre- and post-dosing blood samples were monitored for changes in packed cell volume and changes in content of plasma copper, bilirubin, AST and SDH. Weight changes were also recorded. The animal dosed at twice the recommended level died on day 19 post-dosing of acute copper poisoning. The two dosed at the standard rate remained healthy and put on weight steadily throughout the six months following treatment. Two Welsh Mountain sheep dosed at the standard rate and maintained and examined in the same way likewise showed no signs of copper toxicity.