Efficacy of FRONTLINE® Plus (Fipronil/(S)-Methoprene) and FRONTLINE Gold (Fipronil/(S)-Methoprene/Pyriproxyfen) Against Ixodes scapularis at Twenty Four Hours Following Weekly Tick Infestations on Dogs.

Two separate studies were performed to evaluate the 24-hour efficacy of FRONTLINE ® Plus for Dogs (fipronil/(S)-methoprene, Boehringer Ingelheim, Duluth, GA, USA) and FRONTLINE Gold for Dogs (fipronil/(S)-methoprene/pyriproxyfen, Boehringer Ingelheim, Duluth, GA, USA) against Ixodes scapularis ticks on Days 2, 9, 16, 23, and 30. From a pool of 28 dogs, 24 dogs with the highest tick counts were allocated to one of three treatment groups: Group A comprised eight control dogs treated with 0.5 mL of mineral oil each, Group B comprised eight dogs treated with FRONTLINE Plus (0.67 mL for dogs 5 to 22 lbs, or 1.34 mL for dogs 23 to 44 lbs), and Group C comprised eight FRONTLINE Gold-treated dogs (0.67 mL for dogs 5 to 22 lbs, or 1.34 mL for dogs 23 to 44 lbs). The first study compared Groups A and B, and the second study compared Groups A and C. Both studies utilized the same control dogs. Both studies were performed at the same time, on the same days, at the same facility. Combining the two studies, 24 dogs were treated with mineral oil (Group A), FRONTLINE Plus (Group B), or FRONTLINE Gold (Group C) on Day 0. All dogs were infested with 50 live, unfed Ixodes scapularis ticks on Days 1, 8, 15, 22, and 29 post-treatment, and all ticks were removed and counted 24 hours later on Days 2, 9, 16, 23, and 30. Dogs treated with FRONTLINE Plus had significantly (p<0.01) fewer live ticks than the controls at 24 hours post-infestation on Days 2, 9, 16, 23, and 30. Geometric mean efficacy was 100% at Days 9 and 23; >99% at Days 2 and 16; and 93.2% at Day 30. Dogs treated with FRONTLINE Gold had significantly (p<0.01) fewer live ticks than the controls at 24 hours post-infestation on Days 2, 9, 16, 23, and 30. Geometric mean efficacy was 100% at Days 9, 16, and 23; >99% at Day 2; and 98.4% at Day 30. Both products demonstrated excellent efficacy and persistent activity against Ixodes scapularis tick infestations at 24 hours for a full 30 days. [ABSTRACT FROM AUTHOR]