Experimental copper and heliotrope intoxication in sheep: morphological changes

Young Merino wethers were used to determine the effects of copper and heliotrope, fed together or separately, on the development of toxicity and the concentration of trace elements in the liver and kidney. In one experiment copper and heliotrope were given concurrently, in a second experiment heliotrope was fed for 12 weeks and copper administration commenced 8 weeks later. The 10 sheep fed heliotrope alone did not show signs of clinical illness but one died and was found to have severe liver damage. Eleven sheep were given copper alone and three developed the clinical signs and lesions of haemolysis. Fourteen sheep were given copper and heliotrope and 13 became ill. Of these, three developed haemolysis, eight became jaundiced and two became weak without developing jaundice. The concentrations of copper in the livers of control and heliotrope-treated sheep, were comparable. In the animals given copper alone, the concentration of copper in the liver was twice as high as that in controls and in those given heliotrope and copper, it was three times as high as in the liver of control sheep. Feeding heliotrope alone induced the histological changes of pyrrolizidine alkaloid toxicity in the liver, but this was not associated with an excessive accumulation of copper or the development of clinical illness. However, it did predispose the animals to the effects of a second toxin since giving heliotrope and copper concurrently, or giving copper subsequent to feeding heliotrope, markedly enhanced the toxicity of the two substances and caused an excessive accumulation of copper in the liver.