Abstract
BackgroundAmblyomma americanum and Rhipicephalus sanguineus (sensu lato) nymphs commonly feed on and transmit pathogens to dogs (Canis familiaris). Control of immature and adult tick life stages is necessary to fully protect animals. We evaluated efficacy of oral fluralaner (Bravecto®) against induced infestations with A. americanum and R. sanguineus (s.l.) nymphs on dogs in two experiments.MethodsIn each experiment, 10 dogs were administered oral fluralaner chewable tablets one time on Day 0 at a targeted minimum dose of 25 mg/kg body weight and 10 dogs remained non-treated controls. Dogs were infested with two groups of 50 A. americanum nymphs and two groups of 50 R. sanguineus (s.l.) nymphs on Days -1, 6, 28, 56 and 84. At 48 h and 72 h post-infestation, nymphs were collected from dogs, assessed as live or dead, and enumerated into categories defining attachment and engorgement status. Fluralaner efficacy was determined in separate analyses against all live nymphs and against live-fed nymphs, i.e. live nymphs that were attached to dogs at the time of collection and/or were engorged. Fluralaner was considered effective when mean numbers of live ticks were reduced in fluralaner-treated dogs by ≥ 90%.ResultsFluralaner efficacy against all live and live-fed A. americanum nymphs in the first experiment was > 94% on all collection days. Efficacy against all live R. sanguineus (s.l.) nymphs in the first experiment was > 96% on all collection days excluding the 48 h counts for infestations on Days 28 (83.7%), 56 (82.9%) and 84 (86.7%); efficacy against live-fed R. sanguineus (s.l.) nymphs was > 95% on all 48 h/72 h count days. Fluralaner efficacy against all live A. americanum nymphs in the second experiment was > 93% on all collection days for 8 weeks excluding the 48 h count for infestation on Day 56 (87.8%); efficacy against live-fed A. americanum nymphs was > 91% on all count days for 8 weeks. Efficacy against all live R. sanguineus (s.l.) nymphs in the second experiment was > 91% on all 72 h collection days except for infestations on Days 28 (76.8%) and 56 (86.3%); efficacy against live-fed R. sanguineus (s.l.) nymphs was 100% on all 72 h count days.ConclusionsA single administration of oral fluralaner to dogs is effective against A. americanum and R. sanguineus (s.l.) nymphs for up to 12 weeks.
Highlights
Amblyomma americanum and Rhipicephalus sanguineus nymphs commonly feed on and transmit pathogens to dogs (Canis familiaris)
Long suspected as a vector of Rickettsia rickettsii, A. americanum was recently experimentally demonstrated to transmit this pathogen to dogs as both nymphal and adult stages [9, 10]
We present the results of two Good Clinical Practice (GCP) laboratory experiments evaluating the efficacy of oral fluralaner against A. americanum and R
Summary
Amblyomma americanum and Rhipicephalus sanguineus (sensu lato) nymphs commonly feed on and transmit pathogens to dogs (Canis familiaris). A tick species that feeds on a variety of animals and is well-documented on dogs (Canis familiaris) during larval, nymphal, and adult stages is Amblyomma americanum, the lone star tick [4,5,6]. Amblyomma americanum are known to transmit numerous infectious agents as nymphs and adults to dogs and humans including Ehrlichia chaffeensis and Ehrlichia ewingii [5,6,7,8]. Long suspected as a vector of Rickettsia rickettsii, A. americanum was recently experimentally demonstrated to transmit this pathogen to dogs as both nymphal and adult stages [9, 10]. Infected R. sanguineus (s.l.) nymphs, in particular, were implicated in a R. rickettsii outbreak in Arizona in 2003 involving human fatalities; experimental data confirmed vector competence of immature stages of R. sanguineus (s.l.) [17,18,19]
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