Shelter dogs as patients and predictors of tick risks in Ohio

Ohio is situated at the leading edge of range expansion for several medically important ticks, and consequently there’s been emergence of several tick-borne diseases. Domestic dogs are susceptible to numerous tick-borne pathogens, some of which cause substantial clinical disease. Domestic dogs can also be valuable sources of ticks for surveillance and can serve as sentinels for the risk of exposure for humans since humans are often bitten by the same ticks and susceptible to many of the same tick-borne pathogens. To better understand the breadth of ticks and tick-borne pathogens of concern to human and companion animal health in Ohio, paired tick and blood samples were collected from shelter dogs in southern Ohio. We conducted molecular and serological assessments for Anaplasma spp., Ehrlichia spp., spotted fever group rickettsiae, and Borrelia burgdorferi, and analyzed risk factors associated with exposure. Between 2020-2021, a total of 273 dogs from nine different county shelters were included in the study. From these, 268 ticks were collected for identification yielding 151 Amblyomma americanum, 73 Ixodes scapularis, 42 Dermacentor variabilis, and 1 Haemaphysalis longicornis, marking the first detection of this exotic tick in the state of Ohio. Overall, 118 dogs (43.5%) had antibodies to at least one tick-borne pathogen and 58 (24%) had antibodies to multiple tick-borne pathogens. Seropositivity was associated with dog size, age, and the presence of ticks during physical exam. Our results highlight the value of shelter dogs as sentinels and have implications for tick-borne disease diagnostics in resource-limited settings like shelter medicine.