First case of clinical canine hepatozoonosis in Ukraine.

Canine hepatozoonosis is caused by the tick-borne protozoans Hepatozoon canis and Hepatozoon americanum (Apicomplexa, Hepatozoidae). While H. americanum is widespread in the south-central and south-eastern United States, H. canis is documented in Europe, Africa, Asia, and South America, and is transmitted to dogs by ingesting infected ticks, primarily Rhipicephalus sanguineus. In Europe, this vector is mainly distributed in the Mediterranean region but endemic areas within Central Europe have also been reported, possibly facilitated by climate change. A mixed-breed male puppy, ∼3-7 months-old, evacuated from Kherson City, Ukraine, was admitted to a private veterinary clinic in Kyiv in August 2023. There was no information about the owner and history of the animal. Physical examination evidenced fever, anorexia, lethargy, mild dehydration, and pale mucous membranes. Alopecia, purulent skin ulcers, and pruritus were also observed. On day 1 of admission, a 34 % hematocrit and elevated leukocyte counts, particularly granulocytes and lymphocytes, were observed. H. canis gamonts were detected in stained blood smears and confirmed by specific PCR. Treatment was initiated with imidocarb at 6.6 mg/kg i.m. at 15-day intervals for six weeks, and doxycycline 10 mg/kg orally once daily for two weeks. Blood counts improved between towards day 16, with initial increase and subsequent normalization of hematological parameters. Hepatozoon-PCR was still positive on day 16. The dog made a full recovery, and no further tests were done thereafter. The systemic clinical signs were likely parasite-induced. H. canis and its vector R. sanguineus are being increasingly reported in Europe outside of their original geographical distribution, the Mediterranean basin. This case confirms the geographical expansion of this protozoan parasite.