Water immersion of dogs close to the time of topical fluralaner treatment does not reduce efficacy against a subsequent experimental challenge with Rhipicephalus sanguineus (sensu lato)

Background: fluralaner is a novel systemic ectoparasiticide for dogs and cats providing immediate and persistent flea- and tick-control after a single topical dose. prescribing directions recommend waiting 72 h following topical administration before immersing dogs in water. the objective of this study was to determine whether water immersion immediately prior to treatment or earlier than 72 h post-treatment reduced subsequent treatment efficacy. methods: forty (n = 40) dogs were blocked on tick carrying capacity into 5 experimental groups and all but one of the groups (untreated control) were treated topically with fluralaner (bravecto® spot-on solution,merck animal health,madison,nj,usa) at the commercial dose. three of the four remaining groups were immersed in 38-40 °c water for a 5 min bath - either 1 h before treatment; 12 h after treatment; or 24 h after treatment. seven days after treatment all dogs were challenged with 50 rhipicephalus sanguineus (sensu lato) ticks and after 24 h attached ticks were counted and removed. results: efficacies (compared to the untreated control group) were: 99.3% for no water immersion; 99.6% for immersion 1 h before treatment; 99.3% for immersion 12 h after treatment; and,100% for immersion 24 h after treatment. conclusions: water immersion of dogs around the time of topical fluralaner administration did not reduce subsequent systemic acaricidal efficacy. © 2017 the author(s).