METASTATIC MINERALIZATION IN BRUSHTAIL POSSUMS (TRICHOSURUS-VULPECULA) FROM KAWAU-ISLAND

Aims. To describe the nature and incidence of metastatic mineralisatio n in brushtail possums (Trichosurus vulpecula) caught on Kawau Island. Methods. Wild-caught possums were individually housed in captivity ov er a 24-month period and fed a cereal-based mash diet. Possums that be came debilitated were examined post mortem for evidence of metastatic mineralisation of the heart, major blood vessels and kidneys. Serum an d aortic segments were collected from affected animals and were analys ed for mineral composition. Non-debilitated animals and possums that w ere experimentally poisoned with cholecalciferol were examined as a co mparison. Results. Fifteen of 42 possums (36%) captured on Kawau Islan d and housed in captivity were debilitated as a result of metastatic m ineralisation of the walls of the aorta and/or of the kidney tubules, with four further possums having evidence of mineralisation when human ely killed. Phosphate and ammonium deposits were found in the aorta, a nd calcium deposits in the kidney tubules. Serum phosphorus and calciu m levels were elevated in the debilitated animals. Similar lesions wer e found in only one of 288 possums captured from other North Island ar eas and housed in captivity over the same time period. Conclusion. Pos sums from Kawau Island appear to be more predisposed to metastatic min eralisation than possums from other areas of the North Island. The les ions observed in these possums were similar to those caused by choleca lciferol poisoning.