Field study to investigate the effectiveness and safety of a novel orally administered combination drug product containing milbemycin oxime and lotilaner (Credelio Plus) against natural flea and tick infestations on dogs presented as veterinary patients in Europe.

Background: A pivotal randomised, blinded, positive-controlled, multicentre, European field study was conducted to evaluate the effectiveness and safety of a novel combination tablet of lotilaner and milbemycin oxime (Credelio Plus) administered orally to client-owned dogs naturally infested with fleas and/or ticks.

Methods: In this field study, households with flea- or tick-infested dog(s) were enrolled on Day 0 into the study to provide data for either the tick or flea infestation cohorts. Households were randomised in a 2:1 ratio to receive either the combination investigational product (IP, Credelio Plus tablets) or the control product (CP: Nexgard Spectra tablets). Dogs were administered IP (flea cohort n = 135; tick cohort: n = 147) or CP (flea cohort: n = 67; tick cohort: n = 74) once every 4 weeks for a total of three times at a dose rate of 20.0-41.5 mg/kg bodyweight lotilaner and 0.75-1.53 mg/kg bodyweight milbemycin oxime (IP) or as recommended (CP). Percentage reduction was calculated by comparing individual dog flea and tick counts at each assessed post-treatment time point to their respective baseline (pre-treatment) infestation. Resolution of the clinical signs of flea allergy dermatitis (FAD) was assessed in flea-allergic dogs on the days that flea counts were performed.

Results: Flea effectiveness of Credelio Plus after 3 consecutive monthly treatments was 100% against Ctenocephalides felis, C. canis and Pulex irritans. Tick effectiveness of Credelio Plus over the same time frame was 99.3% for Ixodes ricinus and 100% against Rhipicephalus sanguineus (s.l.). Flea effectiveness of the CP after three consecutive monthly treatments was 100% against C. felis, C. canis and P. irritans. Tick effectiveness of the CP over the same time frame was 99.8% for I. ricinus and 100% against R. sanguineus. Credelio Plus was well tolerated based on the safety assessments in all treated dogs in this field study. Within both treatment groups there was a reduction in total FAD scores from baseline.

Conclusions: This pivotal European field study demonstrated the excellent effectiveness and safety of a combination of lotilaner and milbemycin oxime (Credelio Plus) administered orally to dogs naturally infested with fleas and/or ticks.