Frédéric Beugnet

Insecticide and acaricide molecules and/or combinations to prevent pet infestation by ectoparasites.

External antiparasitic drugs used in cats and dogs have evolved in terms of active ingredients but also regarding formulations. Old chemical groups have been supplanted by phenylpyrazoles, neonicotinoids, oxadiazines, spinosyns or others which are entering the veterinary market. In addition to insecticides-acaricides, insect and mite growth inhibitors (IGRs) have emerged. These IGRs are used in animals or in the environment, either alone or in combination with insecticides-acaricides. The notion of antiparasitic treatment has evolved to the concept of prevention of ectoparasite infestation but also of transmitted diseases through the introduction of formulations providing long-lasting activity. At the same time, ease-of-use has been improved with the development of spot-on formulations. Progress has also been achieved through the development of antiparasitic drugs providing control of both external and internal parasites.

Transmission of Ehrlichia canis by Rhipicephalus sanguineus ticks feeding on dogs and on artificial membranes.

A South African strain of Ehrlichia canis was isolated and used to infect a laboratory-bred Beagle dog. Rhipicephalus sanguineus nymphs, which fed on this dog, moulted to adult ticks which carried infection rates of E. canis between 12% and 19% and were used in a series of in vivo and in vitro experiments. Five groups of 6 dogs were challenged with the infected R. sanguineus ticks, which were removed 24h, 12h, 6h or 3h after the ticks had been released onto the dogs. The animals were monitored for fever and thrombocytopenia and were considered infected if they became serologically positive for E. canis antibodies as well as PCR positive for E. canis DNA. Seven dogs became infected with E. canis in the following groups: Group 1 (24h tick challenge) 1 out of 6; Group 2 (12h) 1 of 6; Group 3 (6h) 2 of 6; Group 4 (6h) 2 of 6 and Group 5 (3h) 1 out of 6. Six of those 7 infected dogs developed fever and a significant thrombocytopenia. One dog did not show any symptoms, but seroconverted and was found PCR positive on several occasions. Five additional dogs were PCR positive on one test sample only but were not considered infected because they did not develop any specific E. canis antibodies. In vitro, R. sanguineus ticks attached and fed on bovine blood through silicone membranes with attachment rates up to 72.5% after 24h increasing to 84.2% at 72 h. The ticks transmitted E. canis as soon as 8h post application as demonstrated by E. canis DNA found in the nutritive blood medium. In conclusion, transmission of E. canis by R. sanguineus ticks starts within a few hours after attachment, which is earlier than previously thought. These findings underpin the need for acaricides to provide either a repellent, an anti-attachment and/or a rapid killing effect against ticks in order to decrease the risk of transmission of E. canis.

Assay of fipronil efficacy to prevent canine monocytic ehrlichiosis in endemic areas

Our objective was to evaluate the efficacy of fipronil for the prevention of Ehrlichia canis transmission to dogs by Rhipicephalus sanguineus in two endemic areas situated in Africa (Dakar and Djibouti). We carried out controlled trials in kennels for 1 year on 248 dogs, mainly police dogs and military working dogs. Eight groups were studied in a multi-centre study. Fifty five fipronil treated dogs were located in two separated kennels (G3, 37 dogs in Djibouti and G8, 18 dogs in Dakar). G1 (66 dogs) and G2 (60 dogs) were untreated control groups located in Djibouti, whereas G4 (32 dogs), G5 (13 dogs), G6 (18 dogs) and G7 (4 dogs) were the control groups located in Dakar. The epidemiological status of each group is known. G1 and G2 dogs were not kept in kennels, whereas G3, G4, G5, G6, G7, G8 dogs were housed in equivalent kennels. Tick infestation, clinical status and Ehrlichia seroprevalence were assessed during 1 year (duration of the study). Dog treated with fipronil showed neither canine monocytic ehrlichiosis (CME) nor tick infestations. In all groups of untreated control animals, R. sanguineus tick infestations were frequent, particularly in kennels (G5, G6 and G7) as well as morbidity and mortality due to CME. E. canis infection rates were low for fipronil treated animals: 2.7% (1/37) for G3 and 5.5% (1/18) for G8 group. Among control animals, seroprevalence was maximum (100%) in dogs kept in kennels (G5, G6 and G7 groups) and high among native dogs in Djibouti (G1 group): 69.7% (46/66) and in Dakar (G4 group): 50% (16/32). Dogs belonging to expatriate citizens (G2 group) were less likely to be infected: 21.7% (13/60). The comparison of serological results among French army dogs and French citizen dogs that were introduced in Djibouti for an average of 10 months shows a statistically significant (P<0.001) difference. Among fipronil treated animals (G3 group), 2 dogs out of 55 seroconverted (3.6%) compared to 13 out of 60 dogs (21.7%) in the control G2 group. The results of our study indicate the preventative efficacy of a fipronil monthly treatment to avoid CME in endemic areas. Epidemiological data concerning animals that live in the same endemic areas are an example of the serious consequences (in terms of mortality and morbidity) that are related to the absence of efficient methods for tick-control. In order to protect dogs that are in transit in endemic areas against tick-transmitted diseases, the use of an adapted acaricide product is recommended.

Parasites of domestic owned cats in Europe: co-infestations and risk factors

BackgroundDomestic cats can be infested by a large range of parasite species. Parasitic infestations may cause very different clinical signs. Endoparasites and ectoparasites are rarely explored in the same study and therefore multiparasitism is poorly documented. The present survey aimed to improve knowledge of the prevalence and risk factors associated with ecto- and endoparasite infestations in owned cats in Europe.MethodsFrom March 2012 to May 2013, 1519 owned cats were included in a multicenter study conducted in 9 veterinary faculties throughout Europe (Austria, Belgium, France, Hungary, Italy, Romania and Spain). For each cat, ectoparasites were checked by combing of the coat surface associated with otoscopic evaluation and microscopy on cerumen samples. Endoparasites were identified by standard coproscopical examinations performed on fresh faecal samples. Risk factors and their influence on parasitism were evaluated by univariate analysis followed by a multivariate statistical analysis (including center of examination, age, outdoor access, multipet status, and frequency of treatments as main criteria) with logistic regression models.ResultsOverall, 50.7% of cats resulted positive for at least one internal or one external parasite species. Ectoparasites were found in 29.6% of cats (CI95 27.3-32.0%). Otodectes cynotis was the most frequently identified species (17.4%), followed by fleas (15.5%). Endoparasites were identified in 35.1% of the cats (CI95 32.7-35.7%), including gastro-intestinal helminths in 25.7% (CI95 23.5-28.0), respiratory nematodes in 5.5% (CI95 4.2-7.0%) and protozoans in 13.5% (CI95 11.8-15.3%). Toxocara cati was the most commonly diagnosed endoparasite (19.7%, CI95 17.8-21.8%). Co-infestation with endoparasites and ectoparasites was found in 14.0% of the cats, and 11.9% harbored both ectoparasites and gastro-intestinal helminths.Age, outdoor access, living with other pets, and anthelmintic or insecticide treatments were significantly associated with the prevalence of various parasites.ConclusionsThis survey demonstrates that parasitism is not a rare event in European owned cat populations. The prevalence of multi-parasitism is significantly greater than expected by chance and hence there is tendency for some individual cats to be more prone to infestation by both endo- and ectoparasites due to common risk factors.

Flea control failure? Myths and realities

Why is it that, despite the proliferation of research on their biology and control, fleas remain such a burden for companion animals and their owners? This review highlights a range of reasons for persistence and apparent treatment failures. It argues that a sustainable approach will require integrated pest management based upon a detailed understanding of the flea life cycle, targeting not only adult fleas but also the immature stages in the environment, combining several modes of control and limiting the risk of chemoresistance. Individual characteristics of the pet and its environment need to be considered. Control of fleas can be achieved, over a timescale of several months, if basic rules are respected.

Comparative speed of efficacy against Ctenocephalides felis of two oral treatments for dogs containing either afoxolaner or fluralaner

A study was designed to compare the efficacy of NexGard(®) and Bravecto™, 2 recently introduced oral ectoparasiticides containing isoxazolines, against fleas (Ctenocephalides felis) on dogs. Twenty-four healthy dogs, weighing 9.2 kg to 28.6 kg, were included in this parallel group design, randomized, and controlled efficacy study. On Day -1, the 24 dogs were allocated to 3 study groups: untreated control; Nexgard(®) treated and Bravecto™ treated. The treatments were administered on Days 0, 28 and 56 for Nexgard(®) (labelled for monthly administration), and once on Day 0 for Bravecto™ (labelled for a 12 week use). Flea infestations were performed weekly with 100 adult unfed C. felis on each dog from Days 42 to 84. Fleas were counted and re-applied at 6 and 12 h post-infestation and removed and counted 24 h post-infestation. The arithmetic mean flea count for the untreated group ranged from 62.9 to 77.6 at 24 h post-infestation, indicating vigorous flea challenges on all assessment days. Both the Nexgard(®) and Bravecto™ treated groups had statistically significantly (p<0.05) less fleas compared to the untreated group on all assessment time points and days. Significantly fewer fleas were recorded for NexGard(®) treated dogs compared to Bravecto™ treated dogs at 6 h post-infestation on Day 56, 63, 70, 77 and 84 and at 12 h post-infestation on Days 70 and 84. No statistically significant (p<0.05) differences were recorded between the treated groups at 24 h post-infestation. Efficacies recorded 6 h post-infestation for Nexgard(®) ranged from 62.8% (Day 49) to 97.3% (Day 56), and efficacies ranged from 94.1% (Day 49) to 100% (Days 42, 56, 70 and 84) at 12 h post-infestation. Efficacies recorded for Bravecto™ ranged from 45.1% (Day 84) to 97.8% (Day 42) at 6 h post-infestation, and from 64.7% (Day 84) to 100% (Days 42 and 56) at 12 h post-infestation. Efficacies observed at 24 h were 100% for both products during the study except 99.6% on Day 84 for Bravecto™.

Occurrence of Dipylidium caninum in fleas from client-owned cats and dogs in Europe using a new PCR detection assay

Ctenocephalides fleas are not only the most prevalent ectoparasites of dogs and cats but also the intermediate host of the cestode Dipylidium caninum. Due to the poor sensitivity of coproscopy to diagnose cat and dog infestation by Dipylidium, few epidemiological data are available on its prevalence among pet populations. A new PCR method was developed to specifically identify D. caninum rDNA inside single fleas. The PCR test was then applied to 5529 fleas of Ctenocephalides genus, 2701 Ctenocephalides felis fleas (1969 collected on 435 cats and 732 on 178 dogs) and 2828 Ctenocephalides canis fleas collected from 396 dogs. Precisely, 4.37% of cats were infested by a flea population infected with D. caninum. Out of the 1969 C. felis from cats, 2.23% were found to be infected with Dipylidium. From the 396 dogs infested with C. canis, 9.1%% were infested with the Dipylidium infected fleas, which is significantly higher than the observation made in cats (p=0.03). Moreover, 3.1% of the C. canis fleas were found to be infected with Dipylidium, which is not significantly different than in C. felis. Looking at the number of infected fleas in the positive samples (at least one PCR positive flea in a sample), the infestation rate in samples was varied from 3 to 100% with an average of 19.7% which is in favour of easy and regular Dipylidium reinfestations of both cats and dogs in households. For the first time, the spread of D. caninum between fleas and dogs and cats is confirmed throughout Europe.

Prevention of transmission of Ehrlichia canis by Rhipicephalus sanguineus ticks to dogs treated with a combination of fipronil, amitraz and (S)-methoprene (CERTIFECT®).

The ability of CERTIFECT(®) (a combination of fipronil, amitraz and (S)-methoprene) to prevent transmission of Ehrlichia canis was studied in two groups of eight dogs. One group was treated with CERTIFECT while the other group remained untreated. All dogs were exposed to E. canis-infected Rhipicephalus sanguineus ticks on Days 7, 14, 21 and again on day 28 post-treatment by releasing ticks into the kennels of the dogs to simulate the natural way of infestation. Animals were examined in situ for ticks on Days 9, 16 and 23 and any ticks present were counted and removed on Day 30. The efficacy of CERTIFECT against R. sanguineus was 100%, since no ticks were found on the treated dogs at any time. Clinical examinations (including monitoring body temperature and blood collections for PCR analysis and serology) were performed at intervals throughout the study until Day 56. Five out of 8 untreated control dogs (62.5%) became infected with E. canis, as demonstrated by detection of specific E. canis antibodies and the presence of E. canis DNA in blood samples by PCR. These dogs displayed fever and thrombocytopenia and were rescue-treated with doxycline. None of the 8 dogs treated with CERTIFECT became infected with E. canis, in comparison to the 5/8 control dogs, as confirmed by the lack of specific antibodies and absence of any ehrlichial DNA in blood samples by PCR. CERTIFECT prevented transmission of E. canis and effectively provided protection against monocytic ehrlichiose for at least 4 weeks post treatment.

Comparative efficacy on dogs of a single topical treatment with the pioneer fipronil/(S)-methoprene and an oral treatment with spinosad against Ctenocephalides felis

In the study reported here, the pioneer fipronil/(S)-methoprene topical product (FRONTLINE® PLUS, Merial Limited, Duluth, GA) was compared to the oral spinosad product (COMFORTIS® Elanco, Greenfield, IN) for efficacy against adult fleas and preventing egg production. The product presentations, doses and labelling were the one applicable in the USA. Using a standard protocol, 200 cat fleas of mixed sex were applied to dogs on Days 1, 7, 14, 21, 28, 35, and 42. Dogs were combed to remove fleas 24 hours post-infestation, the fleas were counted, collected, and then reapplied to each dog following completion of their respective count. At 48 hours post-infestation, comb counts were performed and fleas were removed. No fleas were collected from any dog in the fipronil/(S)-methoprene group at any 24 or 48 hours post-infestation assessment throughout the six weeks study, yielding a preventive efficacy of 100%. For the spinosad treatment, efficacy was 100% at 24 hours and 48 hours through Day 16, and thereafter declined. The results observed in the spinosad-treated dogs were highly variable between animals. At the 24 and 48 hours counts following the Day 21 infestation, only five of eight spinosad-treated dogs (62.5%) were flea-free. Following the Day 28 infestation, spinosad efficacy fell to 85% and 89%, for the 24 hours and 48 hours counts, and only two dogs (25%) were flea free, compared to 100% flea-free dogs in the fipronil/(S)-methoprene group. No fleas were collected from the fipronil/(S)- methoprene treated dogs throughout the entire study, therefore, no eggs were collected at any time from any dog in the group. However, in the spinosad group adult fleas were found on dogs starting on Day 21 and by Day 30, 42 eggs were collected from one dog that had 107 adult fleas counted at 48 hours. At Day 37 and Day 49, more than 100 eggs were collected from each dog in the spinosad-treated and control groups.

Efficacy of oral afoxolaner for the treatment of canine generalised demodicosis

The efficacy of oral treatment with a chewable tablet containing afoxolaner 2.27% w/w (NexGard®, Merial) administered orally was assessed in eight dogs diagnosed with generalised demodicosis and compared with efficacy in eight dogs under treatment with a topical combination of imidacloprid/moxidectin (Advocate®, Bayer). Afoxolaner was administered at the recommended dose (at least 2.5 mg/kg) on Days 0, 14, 28 and 56. The topical combination of imidacloprid/moxidectin was given at the same intervals at the recommended concentration. Clinical examinations and deep skin scrapings were performed every month in order to evaluate the effect on mite numbers and the resolution of clinical signs. The percentage reductions of mite counts were 99.2%, 99.9% and 100% on Days 28, 56 and 84, respectively, in the afoxolaner-treated group, compared to 89.8%, 85.2% and 86.6% on Days 28, 56 and 84 in the imidacloprid/moxidectin-treated group. Skin condition of the dogs also improved significantly from Day 28 to Day 84 in the afoxolaner-treated group. Mite reductions were significantly higher on Days 28, 56 and 84 in the afoxolaner-treated group compared to the imidacloprid/moxidectin-treated group. The results of this study demonstrated that afoxolaner, given orally, was effective in treating dogs with generalised demodicosis within a two-month period.