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).

Efficacy of Once-Monthly Doses of Oral Afoxolaner and Afoxolaner/Milbemycin Oxime in a Well-Controlled Study for the Treatment of Canine Generalized Demodicosis

The efficacy of oral treatment with chewable tablets containing afoxolaner 2.27% w/w (NexGard?, Merial, now part of Boehringer-Ingelheim) or 1.875% w/w of afoxolaner and 0.375% w/w milbemycin oxime (NexGard Spectra?, Merial, now part of Boehringer-Ingelheim) was each assessed in eight dogs diagnosed with generalized demodicosis in this parallel group designed, blinded, randomized, single center negative controlled, efficacy study. Afoxolaner at the therapeutic dose (as close as possible to 2.5 mg/kg) was administered to Group 2 dogs, and afoxolaner (as close as possible to 2.5 mg/kg) with milbemycin oxime at 0.5 mg/kg was administered to Group 3 dogs on Days 0, 28 and 56. All dogs were observed once daily for general health starting on Day -7 until Day 84. All dogs were clinically examined on Days -7, -2, 14, 28, 42, 56, 70 and 84. Dogs were weighed on Days -7, -2, 27, 55, and 84. Live mite counts (based on five scrapings per dog and occasion) and clinical assessments, including photographic documentation, were performed on Days -2, 28, 56 and 84. Three monthly treatments with NexGard or NexGard Spectra against generalized demodicosis in dogs were highly effective resulting in a 99.9% and 100% efficacy against mites, respectively. After treatment with NexGard, only three live mites were recovered in five scrapings in one dog on Day 84. After treatment with NexGard Spectra, no mites were recovered in any scraping on any dogs in this group by Day 84. Both treatments resulted in a marked reduction of skin lesions and >90% hair-regrowth at three months after the initial treatment. Reduction of live mite counts was consistent with reduction in the extent and severity of the skin changes. Although the arithmetic mean mite numbers in the negative control group decreased slightly during the study, infection persisted in 7 of the 8 control dogs until Day 84. Both treatment groups of dogs showed a marked improvement of the associated dermatologic signs with steady improvement over the three-month treatment period.