Evaluation of the efficacy of sarolaner (Simparica®) in the prevention of babesiosis in dogs.

Background: Canine babesiosis is a clinically significant emerging vector-borne disease caused among others by the protozoan Babesia canis. The efficacy of sarolaner (Simparica®; Zoetis; at the minimum recommended label dose of 2.0 mg per kg bodyweight) in the prevention of babesiosis was evaluated in twenty-four dogs randomly allocated to either a placebo-treated group or one of two sarolaner-treated groups. At 21 or 28 days after treatment administration, dogs were infested with 50 ± 4 Dermacentor reticulatus ticks of which 25% were confirmed to be infected with Babesia canis. Blood samples were collected from each dog prior to tick infestation and weekly thereafter until 49 days after infestation. The blood was assayed for B. canis antibodies using an indirect immunofluorescence test (IFAT) and for B. canis DNA by PCR assay. A dog was a priori defined as B. canis-positive if it tested positive by both IFAT and PCR at any time during the study.

Results: No treatment-related adverse reactions were recorded during the study. All placebo-treated animals displayed clinical signs due to babesiosis and tested positive on both IFAT and PCR. None of the sarolaner-treated animals displayed any clinical symptoms or tested positive on both IFAT and PCR, resulting in a 100% efficacy in the prevention of canine babesiosis (P = 0.0002).

Conclusion: When given 21 or 28 days before tick infestation, a single treatment with sarolaner at the minimum recommended label dose of 2.0 mg per kg body weight prevented the transmission of B. canis by D. reticulatus to dogs.