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.

Comparison of the Palatability of a New Flavoured Drontal^(■) Plus Tablet(Drontal^(■) Plus Treat 10 kg)and Milbemax^(■) Chewable Tablets When Presented to Privately Owned Dogs

There is an increased need for highly palatable oral dosage forms for dogs and cats, especially in the case of regular or chronic medications. To meet this need of easy application, the original Drontal®Plus tablet, a broad-spectrum anthelminthic, was optimized using a novel formula. A field study was conducted to evaluate the palatability of this new Drontal®Plus formula in comparison to a positive control product (Milbemax®Chewable Tablets) with a well-known high palatability. The study also aimed to get a palatability claim which necessitates the conduct of appropriate studies. 150 privately owned dogs of 38 pure or mixed breeds, six months to twelve years old, and with a weight range of 5 to 50 kg were included. The study was based on a cross-over design, and a standardized acceptance test was used to evaluate and compare the palatability of the two medications. In this study 88% of dogs voluntarily consumed Drontal®Plus Treat 10 kg, and 86.7% accepted Milbemax®Chewable Tablets. In the majority of cases (IVP: 98%, CP: 95%) the tablets were taken directly from the owner’s hand. The new Drontal®Plus tablet showed a high palatability compared to the Milbemax®Chewable Tablets when used in a household study design with privately owned dogs.

Adaptation to a novel host and performance trade-off in host-generalist and host-specific insect ectoparasites

We investigated the performance trade-offs of fleas(Siphonaptera)while adapting to a novel host using two host generalists(Xenopsylla conformis and Xenopsylla ramesis)and one host specialist(Parapulex chephrenis)maintained on their principal hosts(Meriones crassus for Xenopsylla and Acomys cahirinus for P.chephrenis).We asked whether,over generations,(i)a host generalist may become a specialist by evolving the ability to exploit a novel host and losing the ability to exploit an original host and(ii)a host specialist can become a generalist by evolving the ability to exploit a novel host without losing the ability to exploit an original host.We established an experimental line of each species on a novel host(Acomys russatus for Xenopsylla and M.crassus for P.chephrenis)and maintained this line on this host during 23 generations.We compared reproductive performance of progenitors of each line and their descendants when they exploited either original or novel host in terms of egg number and size,hatching success,offspring production,and offspring size.We found changes in performance over generations in female offspring size only.Xenopsylla conformis demonstrated a tendency to become a host specialist(increased performance on the novel host with a concomitant decreased performance on the original host),whereas P.chephrenis demonstrated a tendency to become a host generalist(increased performance on the novel host without a concomitant decreased performance on the original host).We conclude that the probability of generalist to specialist transition,and vice versa,is context-dependent and varies between species.