Efficacy of a spot-on combination of fluralaner plus moxidectin (Bravecto Plus) in cats following repeated experimental challenge with a field isolate of Ctenocephalides felis.

Background: A spot-on formulation of fluralaner plus moxidectin has been designed to provide long-term protection against fleas and ticks, prevent heartworm disease and treat gastrointestinal nematode infections in cats. The objective of this study was to determine the efficacy of this product against fleas collected from a household with repeated fipronil failures following owner-administered treatments.

Methods: Thirty cats were randomized to three equal groups: (A) untreated controls; (B) to receive a single application of fluralaner plus moxidectin (Bravecto Plus) at 40 mg/kg and 2 mg/kg body weight, respectively; and (C) three applications at one month intervals with a spot-on formulation of fipronil and (S)-methoprene (Frontline Plus) at 0.5 ml manufacturer recommended dose. Flea challenges were completed on Days -6 (for randomization), -1, 7, 14, 28, 42, 56, 70, 77, 84 and 91. Flea counts were completed 48 hours after initial treatment and 48 hours following each subsequent challenge.

Results: Fleas were found on all control and all fipronil and (S)-methoprene treated cats at every assessment. From Day 2 to Day 93, all cats in the fluralaner plus moxidectin group were flea-free, with one exception (Day 58; three fleas counted on one cat); control group flea counts ranged between 34-109, and fipronil and (S)-methoprene group counts ranged between 1-79. At each assessment after Day 0, compared to the control group, geometric mean flea counts were significantly lower in the fipronil and (S)-methoprene group (P ≤ 0.04) and in the fluralaner plus moxidectin group (P < 0.001), and mean flea counts in the fluralaner plus moxidectin group were significantly lower than those of the fipronil and (S)-methoprene group (P < 0.001). The efficacy of fluralaner plus moxidectin, based on geometric means, was 100% at each assessment post-Day 0 except on Day 58 when efficacy was 99.7%. In the fipronil and (S)-methoprene group efficacy ranged between 30.6-65.6%.

Conclusions: These findings demonstrate complete efficacy of fluralaner plus moxidectin against a flea isolate that was not controlled by fipronil and (S)-methoprene. This study provides confirmation of the consistent, sustained efficacy of topically applied fluralaner in the treatment and control of flea infestations in cats.