Hepatogenous chronic copper poisoning in sheep

Harjit Singh Deol

This project was initiated (a) to study the lesions and clinical symptoms which develop when sheep ingest pyrrolizidine alkaloids from the common heliotrope plant [Heliotropiwn europaeam) together with copper, (b) to investigate the interactions between copper and heliotrope and (c) to determine the effect of thiomolybdate administration in the prevention and treatment of the syndromes. Sheep were fed a pelleted ration based on lucerne and oats with or without chopped heliotrope. Copper was given by mouth, in gelatin capsules. Biochemical, histopathological, electronmicroscopic and bile cannulation techniques were used during this study. Feeding heliotrope alone did not raise the copper concentration in the liver above that of controls, but giving copper and heliotrope together, resulted in the copper concentration in the liver being increased to three times that found in sheep fed control and heliotrope diets and twice the concentration found in sheep administered copper only. One sheep from the group fed copper alone developed haemolysis and none of the sheep in the heliotrope group were affected clinically. All the sheep fed copper and heliotrope together were affected clinically and all had severe liver damage. These results demonstrated that a marked synergism exists when copper and heliotrope, are given together. The synergism is seen in the increased severity of clinical symptoms and liver damage and in a greater accumulation of copper in the liver. Similar results were found when copper was administered eight weeks after the cessation of heliotrope feeding. The exact mechanism of excess copper accumulation in the liver due to feeding of copper together with heliotrope, is not known. It was thought that heliotrope may be decreasing the biliary excretion of copper, thus leading to its accumulation in the liver. The results from the present study indicated that heliotrope does decrease the biliary excretion of copper. The administration of thiomolybdate to sheep given heliotrope and copper did reduce the copper content of the liver but it did not effect the development of lesions or clinical illness. The results of this small trial indicated that thiomolybdate may be of limited value for the prevention of the copper-heliotrope syndrome in sheep.

Hepatogenous chronic copper poisoning in sheep

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