American canine hepatozoonosis caused by Hepatozoon americanum is an emerging tick-borne disease in the southern USA with severe and often fatal welfare consequences.
American canine hepatozoonosis causes some of the most severe pain recorded in canine tick-borne disease. The parasite invades periosteal tissues surrounding bones, causing constant, intense bone pain that prevents normal movement and severely impairs quality of life. Dogs often adopt a hunched posture and are reluctant to move. Relapses are common even with treatment, and the disease progresses relentlessly over months to years in many cases. The welfare imperative is stringent tick control — particularly preventing dogs from eating ticks by avoiding roaming and using effective acaricides.