Chronic Copper Bilysinate Poisoning in Five Texel Sheep: A Case Report

Copper is an essential trace element but becomes toxic in overexposed animals. Sheep are the domestic species most prone to chronic copper poisoning, as a slight increase in the dietary concentration can lead to liver accumulation and the development of clinical signs in this species. Common sources of copper in the diet are feed additives and mineral supplements, which are commonly used in pigs and poultry. Recently, new copper supplements were registered for animal nutrition, including copper bilysinate. This study describes an episode of presumed chronic copper poisoning in Five Texel sheep, which were exposed to a compound feed containing copper bilysinate. Four weeks after the introduction of the compound feed into the diet, the first animal started to show typical clinical signs of chronic copper poisoning and died, followed by another animal a week later. Despite removing the compound feed from the diet, a third sheep died 3 weeks later. Two animals survived and fully recovered. Necropsy and histology showed characteristic gross and microscopical lesions typical of copper poisoning. The case report highlights the potential toxic effect of copper bilysinate in sheep.