Hepatozoonosis of Dogs and Cats.

Hepatozoon canis and Hepatozoon americanum are tick-borne infections of dogs transmitted by different tick species, with dissimilar geographic distributions, target organs, and clinical syndromes. H canis is transmitted mostly by the brown dog tick Rhipicephalus sanguineus sensu lato, affects hemolymphoid organs, is associated with anemia and other hematologic abnormalities, and is widely prevalent globally, whereas H americanum is transmitted by the Gulf Coast tick Amblyomma maculatum, causes severe myositis, and is an emerging parasite in the southern United States. Treatment of these 2 infections decreases the parasitic load without elimination. Domestic cats are infected with 3 Hepatozoon species.