Speed of kill, repellent (anti-feeding) and acaricidal efficacy of an imidacloprid 10% (w/w) /flumethrin 4.5%
(w/w) collar (Seresto®, Bayer) and a spot-on formulation of fipronil 8.3% (w/v) /(S)-methoprene 10% (w/v)
/eprinomectin 0.4% (w/v) /praziquantel 8.3% (w/v) (Broadline®, Merial) against artificially-induced infestations
with Ixodes ricinus on cats, were assessed in a parallel group design, randomized, controlled study. Twenty-four
cats were included and randomly allocated to treatment groups or non-treated controls. Starting on Day (D) 7
after treatment until D28, cats were each infested with 50 I. ricinus at weekly intervals. Ticks were counted in
situ on the cats at 6, 12 and 24 h and upon removal 48 h after each infestation. Based on arithmetic means,
Seresto® proved to be 100% effective against adult I. ricinus at all assessment times (6, 12, 24 and 48 h after
infestation) throughout the month-long study. Broadline® was 0% to 16.7% effective at 6 h, 26.8% to 50.0%
effective at 12 h, while at 24 h after infestation efficacy peaked at 81.5% on D15 declining to 31.5% on D29.
Based on the 48 h tick counts, the efficacy of Broadline® peaked at 100% on D16 after treatment and decreased
to 83.2% by D30. The Seresto® collar provided significantly faster speed of kill and better persistent acaricidal
effectiveness against Ixodes ricinus on cats compared to Broadline® spot-on. The additional repellent (antifeeding)
effect of Seresto® prevents parasites from taking a blood meal and thereby reduces the risk of vectorborne
disease pathogen transmission.