Toxic effects of mebendazole at high dose on the haematology of red-legged pademelons (Thylogale stigmatica)

OBJECTIVE: To investigate the effects of mebendazole at high dose on the haematology of macropods. DESIGN: Experimental. PROCEDURE: Five red‐legged pademelons (Thylogale stigmatica) were dosed orally with mebendazole at 50 mg/kg/d for 5 to 6 days. Two control pademelons were dosed with water. Regular blood samples were taken for haematology over 20 days. RESULTS: All four treated pademelons sampled at 5 days developed severe leucopenia and neutropenia, moderate lymphopenia, thrombocytopenia, eosinopenia and monocytopenia, as well as bone marrow aplasia within 5 to 11 days after the first mebendazole dose. Four pademelons died unexpectedly or became ill and were euthanased 5 to 11 days after the first dose while the other animal recovered after 5 days of illness. Necropsy revealed systemic infection with opportunistic enteric bacteria, non‐suppurative inflammation in tissues, haemorrhage and ulceration of the gastrointestinal tract. CONCLUSIONS: Red‐legged pademelons rapidly develop bone‐marrow aplasia and subsequent septicaemia after administration of high doses of mebendazole. Mebendazole at high doses should not be used for macropods.