Efficacy of lotilaner (Credelio™ chewable tablets) for preventing Babesia canis transmission to dogs by infected Dermacentor reticulatus ticks

Abstract Background Canine babesiosis is a clinically significant tick-borne disease, caused by different Babesia species. Babesia canis, one of the most important and widespread species in Europe, is transmitted by Dermacentor reticulatus ticks and can cause potentially fatal canine disease. Prevention of pathogen transmission can be achieved by regular tick control and prophylaxis. The present study evaluated the efficacy of a single oral application of lotilaner (Credelio ™ , Elanco) in dogs for blocking pathogen transmission compared to a negative control group. Methods Twenty-four B. canis -negative dogs were allocated to three groups ( n  = 8 each). The two treatment groups were treated once orally with Credelio either on Day 0 or 23, while the negative control was sham-dosed accordingly. All dogs were challenged with B. canis -infected D. reticulatus on Day 28, i.e., 28- or 5-days post-treatment (p.t.), for the lotilaner-treated groups. Tick efficacy was assessed by in situ tick counts 24 and 48 h after infestation (Days 29 and 30) and final tick counts and removals 120 h after infestation (Day 33). Clinical examinations, hematology (blood smear), serology (IFAT) and blood PCR were performed in all dogs systematically and in case of suspected clinical babesiosis. Results A single oral treatment with Credelio 28 or 5 days prior to infestation with B. canis -infected D. reticulatus resulted in 100% blocking efficacy against B. canis transmission, as compared to untreated dogs ( p  B. canis infection. No treated dog seroconverted or showed a positive PCR. The untreated negative controls tested positive for B. canis from Day 35 onward. All negative controls developed B. canis infection by Day 36 (clinical signs, blood smear, PCR). From Day 43 onward, positive IFAT was also observed. Lotilaner administered on Day 0 or Day 23 demonstrated tick efficacy of 99.7 and 100%, respectively (Day 33). Conclusions This study confirmed a single oral application of lotilaner chewable tablets was highly effective (100%) against D. reticulatus , blocking the transmission of B. canis to dogs at the beginning as well as at the end of the monthly treatment interval of Credelio.