A fatal cytauxzoonosis-like disease in cats.

A cytauxzoon-like agent caused fatal disease in 4 domestic cats from separate, rural, heavily wooded premises in southwestern Missouri. Clinical signs included lethargy; pale, icteric mucous membranes; fever; and dehydration. One case of fatal cytauxzoonosis occurred in early September, 1973, and another in September, 1974. Two additional cases were detected in June, 1975. Tick infestations were reported from a variety of animals, including cats, on all premises. Necropsy revealed generalized icterus and petechial and ecchymotic hemorrhages over the surfaces of the heart and lungs. The pericardial sac was distended with clear yellow serous fluid. Large numbers of schizonts characteristic of Cytauxzoon spp were discovered in specimens of liver, lung, spleen, and lymph nodes of all cats. Infection of vascular endothelial cells, a characteristic of cytauxzoonosis, was observed in all organs examined. Piroplasms or ring forms of the agent were observed in erythrocytes of affected cats.