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.

Preference in Dogs of Two Oral Endectoparasiticide Formulations: NexGard Spectra^®(Afoxolaner and Milbemycin Oxime) and Credelio^®Plus (Lotilaner and Milbemycin Oxime)

Fleas and ticks are major ectoparasites of dogs globally. Their control is based on regular treatments with ectoparasiticides, which represent the most important part of veterinary drugs worth around 3 billion Euros per year. In many parts of the world, dogs are also at risk of infection by endoparasites like heartworm, eyeworm, and lungworm. In these areas, endectoparasiticide formulations are used to prevent the risk of ecto- and endoparasite infections. Since 2014, oral formulations of insecticidal-acaricidal drugs have been launched, followed by endectoparasiticide formulations. These oral formulations facilitate the treatment by the owners and are now the market leaders. Intense work has been done during their development to enhance their palatability through their consistence (hard to soft) and their flavors. Palatable oral formulations facilitate the dog-owner relationship and help ensuring compliance. The most recent palatable formulations include isoxazoline as the ecto-parasiticide molecule. They also include anthelmintics (milbemycin oxime or moxidectin + pyrantel) to provide control of parasitic nematodes. Being very similar in terms of spectrum of activity, any differences in palatability may be a key differentiating factor for the owners. The present study was conducted to verify if dogs exhibited a preference between two endectoparasiticide oral formulations, NexGard Spectra® (afoxolaner and milbemycin oxime) and Credelio® Plus (lotilaner and milbemycin oxime). For four consecutive days, 100 dogs were offered the choice between both products and consumption was recorded. If one product was more consumed than the other, it was defined as the preferred product. A total of 375 chewable tablets were consumed over the four days, with a significantly higher consumption (p < 0.0001) for NexGard Spectra® (272 chews, 72.5%) compared to Credelio® Plus (103 chews, 27.5%). Seventy-six dogs showed a preference for a product amongst whom 68 preferred NexGard Spectra® (89.5%) and 8 preferred Credelio® Plus (10.5%), resulting in a preference ratio of 8.5 to 1 for NexGard Spectra® (p < 0.0001).

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.