An experimental investigation of the hepatotoxic and other effects on sheep of consumption of Heliotropium europaeum L. : Heliotrope poisoning of sheep

Abstract

Experiments were conducted in which two flocks of breeding ewes were grazed on natural pastures containing H. europaeum L. A third flock was grazed on an area on which irrigation water was used to favour germination and early growth of the plant. After the sheep had grazed the plant for the first period, a small proportion, from 1 to 7 per cent., died with damaged livers. After they had again grazed the plant during the following year, the death rate from liver disease rose to 50 per cent. in the exploratory experiment, to 38 per cent. in the first controlled flock experiment, and to 70 per cent. in the second controlled flock experiment. Haematogenous jaundice was present in approximately half the sheep that died. Haemoglobinaemia with haemoglobinuria was present, usually in a mild form, in 31 per cent. of the deaths during the second year of the first controlled experiment, and in 5 per cent. during the second year of the second controlled experiment. In the autumn and spring when the pastures were lush, many of the sheep while in good bodily condition died suddenly without being seen to be sick. Later, most of the deaths were in sheep that had lost condition. Clinical pathological examinations showed that the affected sheep commonly exhibited a fall in haemoglobin and a rise in bilirubin in the blood. Tests showed a fall in prothrombin values. There were indications of a fall in plasma albumen, and also a fall in ability to store glucose. Chemical analyses of livers collected from sheep that died showed the copper concentration to be above normal values, approximately 80 per cent. being over 1000 p.p.m. Histopathological examinations of livers showed that the pathognomonic change was an increase in size of the liver cells associated with their increased death rate and loss of regenerative powers. The changes resulted in an atrophic hepatosis with little replacement fibrosis. There was an accumulation of ceroid in the livers, and a terminal occurrence of inclusion globules in the liver cells. Related field investigations confirmed the findings of the experiments, and showed that the liver damage produced by the consumption of H. europaeum predisposed sheep to the haemolytic crisis of chronic copper poisoning.