Efficacy of Afoxolaner Alone or in Combination with Milbemycin Oxime against Rhipicephalus sanguineus Lato Sensu in Naturally Infested Dogs in Colombia

The brown dog tick (Rhipicephalus sanguineus lato sensu) is the tick that most affects dogs worldwide and is therefore the main blood pathogen vector in dogs. The efficacy of afoxolaner 2.7 to 7.1 mg/kg NexGard® (group A) and afoxolaner plus milbemycin oxime 2.5 to 5.4 mg/kg and 0.5 to 1.1 mg/kg respectively NexGard Spectra® (Group B) against R. sanguineus, was evaluated in naturally infected sheltered dogs under high challenging conditions in four different areas of Colombia (Antioquia, Córdoba, Santander, and Meta). Tick counts (alive, dead, attached, and unattached) were performed on treated dogs, the average was calculated for the different areas to evaluate the efficacy of each treatment at six different times post-treatment (24 h, 48 h, 7 d, 14 d, 21 d, 30 d). None of the dogs showed adverse events related to the treatments. The average tick number pre-treatment was 68 in group A and 78.3 for group B indicating a strong natural infection of the dogs and their environment. Efficacy after 24 h against R. sanguineus was always above 90% with ≥97.4% for NexGard® and ≥93.7% for NexGard Spectra®. Consistent results were observed along all the observation periods with final efficacies (day 30) of ≥99.8% and 98.3% for NexGard® and NexGard Spectra®, respectively. In conclusion, both NexGard® and Nexgard Spectra® provided a curative effect and sustained efficacy against Rhipicephalus sanguineus for at least 30 days in highly contaminated shelter environments.

Comparative Efficacy of Frontline Tri-Act^(■) Spot on(Fipronil/Permethrin)versus Seresto^(■) Collar(Imidacloprid/Flumethrin)against Fleas(Ctenocephalides felis)and Ticks(Rhipicephalus sanguineus)on Dogs with Simulation of Bi-Monthly Rain Exposure

The objective of the study was to compare the efficacy of one topical insecticide-acaricide (Frontline Tri-Act?) and of one collar (Seresto?) against fleas (Ctenocephalides felis) and ticks (Rhipicephalus sanguineus) on dogs exposed to bi-weekly water showering. Twenty four (24) dogs were enrolled in the study. A first set of 16 dogs were acclimatised to their cages from Day 1 to 7 and a second set of 8 dogs from Day 163 to Day 169. The 24 dogs were randomly allocated to three groups (1 to 3). Dogs assigned to Group 1 were not treated and served as negative controls. Dogs assigned to Group 2 received the Seresto? collar on Day 0 and dogs in Group 3 received Frontline Tri-Act? on Days 170 and 198. The dogs were observed hourly for four hours after treatment administration for possible adverse reactions. Dogs in Groups 1 and 2 underwent water showering on Days 14, 28, 42, 56, 70, 84, 98, 112, 126, 143 and 157. Dogs in all groups underwent water showering on Days 173, 185, 199 and 213. Dogs were infested with approximately 100 (±4) adult, unfed C. felis fleas only on Days 177, 190, 203, and 217, in alternance with infestations with 50 adult unfed R. sanguineus on Days 182, 196, 210, and 224, to assess sustained efficacy. Fleas and ticks were removed and counted on 24 and 48 hours ± 2 hours after each infestation, respectively. Frontline Tri-Act? was >99% effective against C. felis following an initial and a second monthly administration on dogs that were water showered bi-weekly. The Seresto? collar was from 68.3% to 92.9% effective against C. felis Days 178 to 218 after collar administration. Frontline Tri-Act? was effective from 87.8% to 100% against ticks whereas Seresto collar was effective from 82.2% to 94.2% from Day 184 to Day 226.