Observations on Blood Copper in the Sheep : II.—Chronic Copper Poisoning

Abstract

SUMMARY A detailed study of blood copper in 4 cases of induced chronic copper poisoning in sheep was made. The development of chronic copper poisoning followed a pattern of 3 stages, according to the level of whole blood copper attained. Apart from transient elevation of the RBC Cu level no marked changes occurred during Stage I which lasted from 62 to 104 days. During Stage II an increase in whole blood copper to about twice normal levels was accompanied by a change in plasma colour due to bilirubin, a decrease in liver function and changes in the level of haematocrit. The blood copper levels were a result of changes in both RBC Cu and DR Cu. The excess copper (up to 19 µg./ml.) present in the blood during the crisis of Stage III was seen first in the plasma, as DR Cu, and later in the red blood cells. These changes are comparable in nature, though not in duration, with those which arc observed after a single massive dose of copper. It would appear that the inability of the red blood cell to release its extra copper is responsible, in part, for the level of whole blood copper and the time for which this level persists. The immediate cause of death in 2 of these sheep would appear to have been the acute general toxic effect of copper, while in the other 2, anaemia and uraemia may well have played an additional part.