This was a multicenter, randomized, field efficacy study conducted at veterinary practices in Germany, France, and Spain, which enrolled privately-owned dogs of any breed or gender. The study started in August 2011 and was finished in February 2012. The veterinarians who performed clinical assessments and parasite counts were blinded to the treatment allocation of the dogs. The study design used the individual dog as the experimental unit for statistical analysis of tick infestations and the household as the experimental unit for analysis of flea infestations.

For enrollment in the study, dogs had to have either a visible flea or tick infestation (or both) on initial examination, with observation of at least 4 individual ectoparasites. The dogs also needed to have an appropriate temperament to permit required manipulations for parasite counting; to be 10 weeks or older, at least 2 kg body weight, and sufficiently healthy to follow the study schedule. Dogs were ineligible if the household included a severely ill animal requiring intensive veterinary care, any dog who had received previous ectoparasiticide treatment within the previous 7 to 30 days depending on the expected duration of effect of the treatment, a pregnant or lactating female dog, more than 5 dogs, or other pet species that could harbor fleas and/or ticks (e.g. cats, rabbits, guinea pigs) sharing the same resting area; if insecticide or insect growth regulator had been applied in the household environment within the previous two months; or if the dog would need to spend substantial time at a dog sitter or animal shelter during the study period. Dog owners were briefed on the study protocol and required to sign an informed consent allowing enrollment of their dog(s) in the study.

Dogs were randomly assigned, using a computer-generated list, to receive either Bravecto™ (fluralaner, 25–56 mg/kg body weight once) or a positive control treatment Frontline™ (fipronil, ≥6.7 mg/kg for three sequential times) at a 2:1 fluralaner:fipronil enrollment ratio. All dogs from the same household were treated using the same product. A clinical examination including a descriptive evaluation of skin and hair examinations to document any skin lesions possibly related to FAD was completed. An initial parasite count was performed using the World Association for the Advancement of Veterinary Parasitology (WAAVP) comb-counting method [6] followed by administration of the initial treatment in the veterinary hospital. All dogs that received the oral Bravecto™ (fluralaner) treatment were initially offered the opportunity to eat the tablet voluntarily. If the tablet was refused, the dogs were given the tablet directly into the mouth.

All dogs remained in the owner’s home and were fed their usual diet with access to water according to their normal routine. Grooming, bathing, and swimming were permitted during the study, but not within 3 days prior to a scheduled visit or within 2 days after treatment application. Participating veterinarians and owners were required to collect details on any suspected adverse events throughout the study.

Regular follow-up procedures in weeks 2, 4, 8, and 12 after initial treatment included re-examinations of dogs to document health status and any changes in skin and hair lesions for dogs that originally presented with FAD, followed by parasite counts. In weeks 4 and 8, dogs in the positive control group were retreated after these procedures. Ticks were removed gently with forceps; counted; and categorized as “live or “dead”; ticks were subsequently sent for microscopic identification of the species.

The percentage reduction of ticks in initially infested dogs and percentage reduction of fleas in flea-infested households were calculated for weeks 2, 4, 8, and 12 compared with baseline for both treatments according to the following formula:

Reduction % = x ¯ pre - treatment - x ¯ post - treatment x ¯ pre - treatment · 100

where x ¯ pre - treatment is the geometric mean number of live ticks or fleas at baseline (day 0) and x ¯ post - treatment is the geometric mean number of live ticks or fleas post-treatment (week 2, 4, 8, and 12).

For each visit, non-inferiority of the percentage of parasite-free households was investigated in the Bravecto™ (fluralaner) group compared with the Frontline™ (fipronil) group. The Farrington-Manning test [7] of non-inferiority for the risk difference was used with a level of significance of α=0.025 and a tolerated difference of δ=0.15.

All data for statistical analysis (SAS Institute Inc., Cary, NC, USA, release 9.2) were entered into a computer using the double data entry technique with subsequent comparison of data sets and a plausibility check for missing values, entry errors, and implausible entries.