Copper poisoning in four llamas.

Copper poisoning developed in 1 adult and 3 juvenile llamas after excessive dietary intake of copper resulted in an incorrect copper:molybdenum ratio. Total dietary copper was determined to be 36 mg/kg of feed, with a copper:molybdenum ratio of 16.6:1. Clinical signs associated with the toxicosis included acute onset of anorexia and lethargy. Liver enzyme activities (aspartate amino transaminase, lactate dehydrogenase, gamma-glutamyl transferase) and serum copper concentration were high in specimens obtained within 48 hours before death. Gross necropsy findings were limited to mild hepatomegaly. Histologically, hepatic lesions included acute massive necrosis of hepatocytes with and without bile duct proliferation, double hepatic plates with loss of orientation, anisocytosis, anisokaryosis, and an intralobular mosaic pattern of necrosis involving half of the hepatocytes. Analysis of hepatic copper concentrations suggested that juvenile llamas develop signs of poisoning at lower hepatic copper concentrations, compared with adults.