Enzootic icterus--a form of chronic copper poisoning

The findings of a recent investigation into the epizootiology, course, symptomatology, gross pathology, chemical pathology and prevention of Enzootic Icterus are presented and the findings of previous investigations on these and other aspects are reevaluated. Enzootic Icterus and chronic copper poisoning are shown to be identical in all fundamental features. Both diseases are characterised by sudden onset, high mortality, icterus, anaemia, haemoglobinaemia, methaemoglobinaemia, haemoglobinuria and deeply pigmented kidneys. There are no described microscopic features on which the diseases can be differentiated. Very high levels of copper in the blood, liver and kidneys are found in both diseases. In the present work 36 liver specimens had a mean copper concentration of 701 microgram/g. Of 31 kidney specimens no values under 10 microgram/g were found while the mean was 107 microgram/g. Prevention of Enzootic Icterus by salts of molybdenum given orally confirms the identity. No close relationship with Geeldikkop is found other than the probability that the two diseases may act synergistically. Interpretation of existing knowledge of mineral levels of natural grazing in the enzootic region shows that the levels can account for the presence of chronic copper poisoning, although more investigation is required.