Babesia of Domestic Dogs

Abstract

Canine babesiosis caused by different Babesia species is a protozoal tick-borne disease with worldwide distribution and global significance. Historically, Babesia infection in dogs was identified based on the morphologic appearance of the parasite in the erythrocyte. All large forms of Babesia were designated B. canis, whereas all small forms of Babesia were considered to be B. gibsoni. However, the development of molecular methods has demonstrated that additional Babesia species infect dogs and cause distinct diseases. The geographical distribution of canine Babesia species and thus the occurrence of babesiosis are largely dependent on the habitat of relevant tick vector species, with the exception of B. gibsoni where evidence for dog-to-dog transmission indicates that infection can be transmitted among fighting dog breeds independently of the limitations of vector tick infestation. Knowledge of the prevalence and clinicopathological aspects of Babesia species infecting dogs around the world is of epidemiological and medical interest. Babesia infection causes a disease with clinical manifestations that may vary considerably with the different species and strains involved and with factors that determine the host response to infection such as age, individual immune status, and the presence of concurrent infections or other diseases. Hemolytic anemia with systemic inflammatory responses may lead to tissue hypoxia and organ dysfunction, which account for the clinical signs observed in severe canine babesiosis. Babesiosis caused by large Babesia species is treated with imidocarb dipropionate or diminazene aceturate, while small Babesia species are more resistant to anti-babesial therapy and often require treatment with combinations of other drugs such as atovaquone, azithromycin, and clindamycin. Accurate detection and species recognition are important for the selection of the correct therapy and predicting the course of disease.