Seresto collars protect dogs from Haemaphysalis longicornis ticks

Abstract

BACKGROUND: Haemaphysalis longicornis ticks are reported on dogs from an increasing geographic range. This study aimed to determine the sustained efficacy of Serestocollars (imidacloprid/flumethrin) against experimental infestations of H. longicornis in dogs. METHODS: Twenty-four Beagle dogs previously assessed for their suitability to harbor ticks were included in the study and randomized into three groups of eight dogs each. Two of the groups were treated with collars at different time points: at the first tick infestation, dogs in group 1 had already worn collars for 92&#xa0;days, while dogs in group 2 had received collars only on the previous day, thus allowing evaluation of two different treatment durations at the same point in time. Infestation of the treated groups was conducted at 1, 7, 28, and 56&#xa0;days (group 2) and 92, 119, 147, 168, 196, 227, and 238&#xa0;days (group 1) after collar placement. Group 3 served as untreated control and was infested whenever the dogs of the other two groups were infested. Infestations were conducted using 50 viable, adult, unfed female ticks of a US isolate of H. longicornis per dog. Ticks were removed and counted 48&#xa0;h after each infestation. Health and body weight of the dogs were monitored throughout the study. The efficacy against ticks was calculated for groups 1 and 2 based on arithmetic mean values at each assessment day according to Abbott's formula. The mean post-treatment H. longicornis tick counts were compared statistically between treatments, using an analysis of variance with a treatment effect untransformed tick count. RESULTS: Dogs in the control group were adequately infested at all tick counts. Efficacy was 88.2% on day 3, however well above 90% (i.e., 98.3 to 100%) at all other time points up to day 240. Statistical analysis confirmed significantly different live tick counts (P&#x2009;<&#x2009;0.001) between the treated groups and the control group at all time points. CONCLUSIONS: The 8-month sustained acaricidal efficacy demonstrated by the Serestocollar (imidacloprid/flumethrin) provides a reliable strategy against H. longicornis infestations in dogs.