Abstract Hepatozoon canis infects the haemolymphatic tissues of both domestic and wild dogs, resulting in symptoms such as anemia and lethargy. The transmission of this parasite occurs primarily through Rhipicephalus sanguineus and various other ixodid tick species. A study was conducted to determine the tick vector of H. canis in dogs in the Mashhad region, Khorasan Razavi province, from 2018 to 2021. A total of 976 ixodid ticks were collected from 39 sheepdogs and 76 shelterdogs during activating seasons of ticks. Adult ticks were identified according to general identification keys. The collected female ticks were separated into 81 tick pools according to their species. The hemolymph smear was prepared from engorged and semi-engorged female ticks and stained with the Giemsa method, Then, the DNA of each tick pool was extracted using a commercial kit and analyzed by PCR. Two ixodid species, R. sanguineus and R. turanicus were identified in infested dogs. The frequency of R. sanguineus and R. turanicus infestation in sheepdogs was 80.25% and 19.75% and in shelterdogs 76.5% and 23.5%, respectively. H. canis DNA has only been detected in 15 (18.5%) tick pool samples of R. sanguineus. Immature oocysts of Hepatozoon were detected in two hemolymph smears obtained from engorged female R. sanguineus that tested positive via PCR and were collected from shelter dogs. It is concluded that R. sanguineus was the dominant tick in sheepdogs and shelter dogs in the Mashhad area. Moreover, the results of the molecular and para- sitological examination indicated that R. sanguineus ticks could be a vector of H. canis in dogs in Iran for the first time

Keywords