Fatal cytauxzoonosis in captive-reared lions in Brazil.

Fatal cytauxzoonosis is described in a captive reared lioness (Panthera leo) and its 6-month-old cub. Clinical signs in the lioness included loss of weight, depression, anaemia, loss of hair, dark discolored urine, tachypnoea, nystagmus, deaphness and staggering gait. The cub died after a short period of depression. In the lioness, laboratory examination revealed normochromic normocytic anaemia, neutrophilia, lymphopenia, monocytosis, eosinopenia, thrombocytopenia, proteinuria, pyuria, haematuria and increased. At necropsy the lioness showed marked pulmonary edema and slight gelatinous translucent edema in the mediastinum, petechiae and echymosis disseminated in the serosae, and the intestinal content was red and semiliquid. The cub presented hemothorax, endocardial and pulmonary edema, petechiae in the cardiac serosae, hepatic and splenic congestion and segments of the small intestine with blood stained fluid contents and reddish mesenteric lymph nodes. Histopathological examination of liver, spleen, heart, lungs, intestines, pancreas, mesenteric lymph nodes, kidneys, skeletal muscle, brain and skin revealed large number of intravascular macrophages with their cytoplasm filled with various schizogonic stages of a Theileriidae. Electron microscopy confirmed the presence of schizonts in endothelial-associated macrophages. The diagnosis was established by the finding of the pathognomonic schizonts in macrophages within blood vessels in several organs and tissues from both lions. This is the first report of feline cytauxzoonosis in P. leo and of a confirmed infection by Cytauxzoon felis in felidae in South America.