Tick-borne diseases are of increasing importance in the USA. The majority (75%) of vector-borne diseases is tick-borne, the number of human tick-borne illnesses is steadily increasing, the geographic range of known tick vectors is expanding, and at least seven new tick-borne pathogens have been shown to infect people in the USA within the last two decades. All tick-borne diseases are zoonotic and perpetuation of tick-borne diseases depends on tick parasitism of non-human vertebrate reservoirs. In the USA, the vertebrate reservoirs for human tick-borne disease are primarily rodents. Effective strategies targeting rodent reservoirs are needed to help break the zoonotic transmission cycles and lower the incidence of tick-borne diseases in the USA. This proposal addresses that need by taking advantage of recent advances in veterinary medicine. A new class of orally-administered veterinary drug marketed for dogs (i.e., isoxazoline drugs) displays fast-acting, long-lasting acaricidal activity against ticks that feed on isoxazoline-treated animals. Because of the speed by which these drugs kill ticks after attaching to treated animals, isoxazoline drugs can also block tick transmission of bacterial pathogens to treated dogs. This pilot project will test the efficacy and transmission-blocking abilities of these drugs when given orally to two species of rodents known to be natural reservoirs of Lyme disease in North Dakota ? the white-footed mouse and the red-backed vole. If orally administered isoxazoline drugs work in these rodent reservoir species as well as has been reported in dogs, then the stage will be set to seek funds for a larger R01 project and implement a regional-wide field trial, incorporating isoxazoline drugs in an oral bait formulation to rid rodent reservoirs of their ticks, disrupt zoonotic transmission cycles, and contain the westward spread of Lyme disease across North Dakota.