Normal and toxic zinc concentrations in serum/plasma and liver of psittacines with respect to genus differences

Abstract

Determination of zinc concentration in serum/plasma and tissue of caged and aviary birds is commonly requested by practitioners because of an increased awareness of zinc toxicity. However, interpretation of zinc levels is often based on normal zinc concentrations established for poultry. Also, it is likely that intergenus differences exist in normal zinc concentrations of pet birds. In an attempt to determine normal and toxic concentration ranges, zinc concentrations in liver (n = 276) and serum/plasma (n = 260) collected from psittacines between 1990 and 1998 were analyzed. Zinc concentrations were determined by inductively coupled argon plasma emission spectroscopy analysis. The results were categorized by genus and, when available, by history. Birds that were diagnosed with zinc toxicosis (on the basis of history, clinical examination, pathology, and laboratory findings) were exempt and not included in establishing normal ranges. The results indicate that important differences occur with respect to genera. For example, cockatoos and Eclectus parrots have higher normal zinc concentrations in serum or plasma than other psittacines. In addition, analysis of all the submitted cases suggests that potentially toxic zinc concentrations in livers of psittacines can be well below the range considered toxic in chickens (>200 ppm).