Assessment of afoxolaner efficacy against Otodectes cynotis infestations of dogs

Efficacy and innocuity of lotilaner in the treatment of otodectic mange in ferrets

Otodectes cynotis is a contagious ear mite generally responsible of a parasitic otitis. This prospective study evaluates the efficacy, safety and impact on quality of life (QoL) of oral lotilaner for the treatment of Otodectes infestation in ferrets. Ferrets of weight greater than 500 g, with Otodectes mites confirmed on ear swabs examination and that did not receive an acaricidal treatment in the previous two weeks were included. Oral lotilaner (Credelio 12 mg, ELANCO FRANCE, Sèvres, France) was administered at inclusion day (D0) and 28 days later (D28). Parasitic counts and clinical examination were performed at D0, D28 and D56. A QoL and owner satisfaction questionnaire was given at D0 and D56. Statistical analysis was performed with Shapiro-Wilk test for normality and Wilcoxon test for mean comparison (significance: p<0.05). Eleven ferrets were included, two were asymptomatic. Mean weight was 1.2 kg (0.68-2.66). Mean lotilaner dose was 12.3 mg/kg (9-17.6). Mean eggs, adults or nymphs, larvae, and fragments counts were 30.4 (3-104), 11.2 (1-61), 5.4 (0-36), 3.5 (1-7) respectively at D0; 0, 0, 0.1 (0-1), 0.5 (0-3) respectively at D28; 0, 0, 0, 0.14 (0-1) respectively at D56. Differences were statistically significant from baseline in all cases (p<0.05). Pruritus was absent in all cases at D56. No adverse effects were reported. All owners were "completely satisfied" with the treatment. Mean impact of the disease on QoL was 4.5/18 (SD=4.15) at D0 and 0 at D56 (significant difference, p<0.05). Oral lotilaner appears as a safe, efficient, easy to use and satisfactory treatment of Otodectes cynotis infestation in ferrets.

Efficacy of afoxolaner or the combination of afoxolaner with milbemycin oxime against Otodectes cynotis in naturally infested dogs

Otodectes cynotis, commonly known as "the ear mite," is a highly contagious ectoparasite and a significant cause of otitis externa in canines. The objective of the current study was to determine the efficacy of the isoxazoline afoxolaner (Nexgard®), and the combination of afoxolaner with milbemycin oxime (Nexgard Spectra®), in dogs naturally infested with O. cynotis. In total, 32 infested client-owned dogs from two different sites in Greece were included. The animals were randomly divided into four equal groups based on their infestation score. Group 1 served as the negative control, group 2 received one oral administration of Nexgard (Day 0), group 3 received two monthly oral administrations of Nexgard (Days 0, 30), and group 4 received two monthly oral administrations of Nexgard Spectra (Days 0, 30), according to label instructions. Otoscopic examinations for mites and observations on debris/cerumen in the ears were carried out on Days 0, 15, 30, and 45. A quantitative assessment of ear mites by ear duct flushing and live mite counts was performed on Day 45. The results demonstrated that a single oral dose of afoxolaner and two monthly doses of afoxolaner or afoxolaner with milbemycin oxime resulted in a 99.9% reduction in live mite counts compared to the untreated control group by Day 45. Additionally, treated dogs showed improved clinical symptoms, such as ear cerumen/debris decrease, while untreated dogs experienced worsening symptoms over the study duration. No adverse events were reported. Overall, these results support the use of afoxolaner-based products to treat O. cynotis infestation in dogs.

Activity, selection response and molecular mode of action of the isoxazoline afoxolaner in Tetranychus urticae

BACKGROUND

Afoxolaner is a novel representative of the isoxazolines, a class of ectoparasiticides which has been commercialized for the control of tick and flea infestations in dogs. In this study, the biological efficacy of afoxolaner against the two-spotted spider mite Tetranychus urticae was evaluated. Furthermore, as isoxazolines are known inhibitors of γ-aminobutyric acid-gated chloride channels (GABACls), the molecular mode of action of afoxolaner on T. urticae GABACls (TuRdls) was studied using functional expression in Xenopus oocytes followed by two-electrode voltage-clamp (TEVC) electrophysiology, and results were compared with inhibition by fluralaner, fipronil and endosulfan. To examine the influence of known GABACl resistance mutations, H301A, I305T and A350T substitutions in TuRdl1 and a S301A substitution in TuRdl2 were introduced.

RESULTS

Bioasassays revealed excellent efficacy of afoxolaner against all developmental stages and no cross-resistance was found in a panel of strains resistant to most currently used acaricides. Laboratory selection over a period of 3 years did not result in resistance. TEVC revealed clear antagonistic activity of afoxolaner and fluralaner for all homomeric TuRdl1/2/3 channels. The introduction of single, double or triple mutations to TuRdl1 and TuRdl2 did not lower channel sensitivity. By contrast, both endosulfan and fipronil had minimal antagonistic activities against TuRdl1/2/3, and channels carrying single mutations, whereas the sensitivity of double and triple TuRdl1 mutants was significantly increased.

CONCLUSIONS

Our results demonstrate that afoxolaner is a potent antagonist of GABACls of T. urticae and has a powerful mode of action to control spider mites. © 2022 Society of Chemical Industry.

Transcriptome Analysis of Otodectes cynotis in Different Developmental Stages

The mite Otodectes cynotis is distributed worldwide and parasitism the ear canals of cats and dogs, causing otitis externa. Molecular biology of O. cynotis is poorly understood, with only a few genes being deposited in public databases. In the present study, we aimed to perform transcriptome analysis of O. cynotis using SMRT and Illumina sequencing of RNA from different development stages. SMRT-Seq of O. cynotis demonstrated 5,431 final transcripts, including 406 long non-coding RNAs and 2,698 differentially expressed genes (DEGs), including 1,357 up-regulated genes and 1,341 down-regulated genes between adult mites and nymph/larva. A total of 397 putative allergen genes were detected, 231 of which were DEGs. Among them, 77 were homologous of known mite allergens. The expression level of allergen genes hints at the pathogenicity of mites in different life stages, and the protein interaction network analysis could identify possible key genes in the pathogenic mechanism. Intriguingly, Gene Ontology analysis showed that most of the (DEGs) were associated with the terms hydrolase activity and proteolysis. Kyoto Encyclopedia of genes and genomes (KEGG) analysis identified drug metabolism-cytochrome P450 signal pathway as one of the top pathways. SMRT-Seq of the full-length transcriptome of O. cynotis was performed first, and a valuable resource was acquired through the combination analysis with the Illumina sequencing data. The results of our analyses provide new information for further research into Otodectes cynotis.

Efficacy of afoxolaner for the treatment of ear mite infestation under field conditions

Otodectes cynotis is a commonly occurring surface mite that can be easily transmitted between suitable hosts, including dogs, causing otocariosis. The activity of the systemic insecticide afoxolaner against O. cynotis has been tested once under experimental conditions, showing a high efficacy. The present study aimed to i) assess the efficacy of two consecutive monthly oral administrations of afoxolaner (NexGard®) against O. cynotis in naturally infested dogs under field conditions and ii) evaluate its impact in reducing bacteria or fungal secondary infections. Dogs, positive for O. cynotis (n = 20), were included in the study and allocated in two groups of ten animals each (G1, control group, and G2, treated group). The first group of ear mite-infested dogs was treated with a placebo, while afoxolaner was administered orally to the second group of dogs at Day 0 (D0) and Day 30 (D30), following label instructions. Otoscopic assessments, deep-swab method and swab samples were performed on all dogs (Days 0, 30, 42) to evaluate the presence or absence of live mites and their number throughout the study, as well as to conduct bacterial and fungal assessments. No adverse events likely related were recorded throughout the study. By Day 42 (D42), all dog's ears were flushed to recover ear mites. All treated dogs became negative, as well as two dogs of the control group. The treatment efficacy of afoxolaner was 100 % based on the arithmetic means of the live mite counts. The clinical scores did not change significantly in the control group, whereas they significantly improved in the treated one from D0 to D30 (p-value = 5.47 10^-5). No live mites were present in the afoxolaner-treated group at D42 (p-value = 0.00073). In this field study, two oral administrations of afoxolaner at the recommended dose allowed a complete cure of the infestation. Bacterial and Malassezia pachydermatis infections were detected in both groups, although no significant trend was associated to the ear mite treatment.

Efficacy of afoxolaner (NexGard®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs

New World screwworm (NWS) myiasis is an infestation by Cochliomyia hominivorax larvae that consume the living tissue of warm-blooded animals, including humans. Domestic dogs are among the potential hosts of these flies that lay their eggs on the edges of wounds. NWS myiasis cases can be fatal if untreated. Treatment with parasiticides must be fast-acting, long-lasting and show 100% efficacy, since open wounds can be reinfested. Afoxolaner is a molecule from the isoxazoline family with proven ectoparasiticide action against fleas, ticks and mites in dogs. Fourteen healthy client-owned dogs, naturally infested by C. hominivorax larvae, were treated with afoxolaner (NexGard®) as per label recommendations, providing at least the minimum dosage of 2.5 mg/kg. Maggot infestations were classified as light (fewer than 10 larvae), mild (from 10 to 20 larvae) or severe (more than 20 larvae), according to the number of larvae found in the wound and/or collected from the ground after treatment. Twenty-four hours post-treatment, infested lesions were carefully inspected and collected larvae were counted and classified as live or dead. All maggots were identified as second and third instar larvae of C. hominivorax and were found dead within 24 h after treatment, demonstrating 100% larvicidal efficacy against C. hominivorax.

Efficacy of a novel topical combination of esafoxolaner, eprinomectin and praziquantel against ear mite (Otodectes cynotis) infestations in cats

Esafoxolaner, a purified enantiomer of afoxolaner with insecticidal and acaricidal properties, is combined with eprinomectin and praziquantel, nematodicidal and cestodicidal compounds, in NexGard® Combo, a novel topical endectoparasiticide formulation for cats. The efficacy of this formulation was assessed against Otodectes cynotis in two laboratory studies conducted in South Africa and in the USA with local isolates, and in one field trial conducted in Europe. In each study, cats were randomly allocated to a placebo-treated control group and a novel formulation-treated group. In the laboratory studies, cats were treated at the minimum recommended dose; in the field trial, cats were treated at label dose. All included cats were diagnosed positive for O. cynotis prior to treatment by otoscopy. The main variable of efficacy was a comparison of the number of live O. cynotis collected in both ear canals of all cats in the treated and control groups, one month after treatment. Efficacy of the novel topical formulation exceeded 97% in the three studies. These studies demonstrated the high effectiveness of NexGard® Combo in cats for the treatment of O. cynotis infestations. No health abnormalities were attributed to the treatment in any of the studies.

Current review of isoxazoline ectoparasiticides used in veterinary medicine

The isoxazolines are a novel class of ectoparasiticides with potent inhibitory activity on glutamate- and gamma-aminobutyric acid-gated chloride channel located in nervous system of invertebrates. In recent years, studies have been performed to evaluate the efficacy and safety of isoxazolines against various types of ectoparasites, including fleas, ticks, and mites. As more single and combined isoxazoline products have been approved by the United States Food and Drug Administration and European Medicines Agency, a more comprehensive understanding of isoxazolines becomes essential for veterinary clinical practitioners. This article provides a complete review of isoxazolines with respect to pharmacodynamics, pharmacokinetics, ectoparasiticidal efficacy, and safety, which will provide veterinarians information to allow them to make the best choice of ectoparasiticide for their clients' specific needs.

Insecticidal efficacy of afoxolaner against bedbugs, Cimex lectularius, when administered orally to dogs

The objective of this experimental study was to assess the insecticidal efficacy of afoxolaner (NexGard^®) against bedbugs (Cimex lectularius) on dogs. For each challenge, 20 bedbugs were placed in two chambers positioned in contact to the dog’s skin for 15 min, after which live fed parasites were counted and incubated for survival evaluations. On Day 0, 7 dogs assigned to the treated group were administered afoxolaner orally at the registered dose. All 14 dogs were challenged on Days 1, 7, 14, 21 and 28, and the collected live fed C. lectularius incubated for 72 h (Day 1), and 72 h and 96 h (Days 7, 14, 21 and 28) for survival evaluation. The percent feeding in the control group ranged from 95% to 98.6% and the percent of live fed bedbugs at 96 h ranged from 99.3% to 100% in the control group, demonstrating the viability of the strain and their capacity to feed on dogs. Significantly fewer live fed bedbugs were counted in the treated group, compared to the control group, at all time-points. The reduction of live fed C. lectularius in the afoxolaner group was 41.4% at 72 h after the Day 1 challenge, and 77.2%, 82.7%, 85.0% and 63.5% at 96 h after the Days 7, 14, 21 and 28 challenges, respectively. It is hypothesized that monthly treatment of dogs with afoxolaner could help in preventing a bed bug population from installing in a household if bedbugs bite dogs in the presence of humans.

Recent Advancements in the Control of Cat Fleas

Simple Summary

The cat flea Ctenocephalides felis felis is the most important pest of domesticated cats and dogs worldwide. This review covers the recent advancements in the control of cat fleas. Over the years, there has been an interest in using ecologically friendly approaches to control fleas. To date, no biological, natural, or cultural means have been discovered that mitigate flea infestations. The recent registration of novel topical and oral therapies promises a new revolution in the control of fleas and ticks and the diseases associated with them.

Abstract

With the advent of imidacloprid and fipronil spot-on treatments and the oral ingestion of lufenuron, the strategies and methods to control cat fleas dramatically changed during the last 25 years. New innovations and new chemistries have highlighted this progress. Control strategies are no longer based on the tripartite approach of treating the pet, the indoor environment, and outdoors. The ability of modern therapies to break the cat flea life cycle and prevent reproduction has allowed for the stand-alone treatments that are applied or given to the pet. In doing so, we have not only controlled the cat flea, but we have prevented or reduced the impact of many of the diseases associated with ectoparasites and endoparasites of cats and dogs. This review provides an update of newer and non-conventional approaches to control cat fleas.

Assessment of the insecticidal activity of oral afoxolaner against Phlebotomus perniciosus in dogs

Twelve healthy dogs were included in this laboratory efficacy study. Six dogs were randomly allocated based on body weight to an untreated control group and six to an afoxolaner (NexGard^®) treated group. In the treatment group, afoxolaner was administered orally on Day 0 in accordance with label instructions. On Days 1, 14 and 28, each dog was exposed to 60 unfed female and 10 male Phlebotomus perniciosus sandflies for 1 h. At the end of each exposure period, sandflies were counted and assessed for viability and feeding status. There was no statistical difference in mortality (0.0–5.4%), nor in feeding proportion (61.6–78%) between the control and the treated groups at all 1-h post-exposure assessments. After collection, live fed and unfed sandflies were kept for viability assessments at 48 and 72 h post-exposure. In the untreated control group, the average percentages of live, fed, female sandflies after exposure, on Days 1, 14 and 28, ranged from 51% to 74% at 48 h and from 46% to 57% at 72 h, demonstrating model robustness over the 28 days of the study. Significantly fewer live fed sandflies were recorded for the afoxolaner treated group (p < 0.01). The insecticidal efficacy was 100%, 95.9% and 75.2% at 48 h post Days 1, 14 and 28 exposures, respectively, and 100%, 100% and 86.3% at 72 h post Days 1, 14, and 28 exposures, respectively. A single administration of oral afoxolaner (NexGard^®) to dogs significantly killed P. perniciosus sandflies 48 and 72 h after blood feeding for 1 month.

Treatment of canine sarcoptic mange with afoxolaner (NexGard®) and afoxolaner plus milbemycin oxime (NexGard Spectra®) chewable tablets: efficacy under field conditions in Portugal and Germany

The efficacy of NexGard^® and NexGard Spectra^® against sarcoptic mange in dogs was evaluated in a clinical field study. Skin scrapings from dogs presenting signs suggestive of sarcoptic mange were examined to confirm infestation. A total of 106 dogs were screened at eight sites in Portugal and Germany. In all, 80 dogs that had demonstrated ≥5 live Sarcoptes mites in five skin scrapings were enrolled, scored for specific clinical signs (pruritus; papules and crusts; alopecia), and allocated at random to receive either NexGard^® or NexGard Spectra^® twice, one month apart per label instructions. To determine efficacy, live Sarcoptes mites in five skin scrapings per dog were counted, and clinical signs were scored one month and two months after first treatment and compared to pre-treatment (baseline) values. Based on compliance, 65 dogs were determined to be evaluable cases at the end of the study. The efficacy, in terms of reduction of geometric mean live Sarcoptes mite counts, was 98.9% and 99.7% for NexGard^®-treated (n = 38) and 99.6% and 100% for NexGard Spectra^®-treated dogs (n = 27) at one month and two months after treatment initiation (p < 0.001, both treatments). Both treatments resulted in a significant improvement in pruritus, papules and crusts, and alopecia one month and two months after treatment initiation (p = 0.0001, both treatments). In conclusion, this field study confirms that both NexGard^® and NexGard Spectra^® administered twice one month apart provide an effective and safe treatment against sarcoptic mange in dogs.

Efficacy of two formulations of afoxolaner (NexGard® and NexGard Spectra®) for the treatment of generalised demodicosis in dogs, in veterinary dermatology referral centers in Europe

Background

A multi-centre field trial was conducted to evaluate the efficacy of afoxolaner based chewables (NexGard® or NexGard Spectra®) for the treatment of generalised demodicosis caused by Demodex canis in dogs under field conditions in France, Italy and Poland.

Methods

Client-owned dogs, diagnosed positive for Demodex mites by pre-treatment skin scrapings and presenting clinical signs of generalised demodicosis were included. Dogs were orally treated with afoxolaner three times at monthly intervals. Of the 50 dogs enrolled, 48 completed the whole study. Efficacy of the treatments was assessed monthly by Demodex mite counts and physical examination with special regard to the severity and extension of skin lesions.

Results

Treatments were well tolerated in all dogs and resulted in a rapid reduction of mites, with all post-treatment mite counts significantly lower than baseline. The number of mites was reduced by 87.6%, 96.5% and 98.1% on Days 28, 56 and 84, respectively. In addition, the skin lesion severity and extent scores as well as the pruritus were all significantly lower at all post-treatment visits compared to the pre-treatment assessment.

Conclusions

This clinical field study demonstrated that monthly administrations of afoxolaner in NexGard® or NexGard Spectra®, offered a convenient and reliable solution for the treatment of canine generalised demodicosis.

Efficacy and safety of sarolaner in the treatment of canine ear mite infestation caused by Otodectes cynotis: a non-inferiority study

BACKGROUND

Various treatments are available for ear mite infestations in dogs.

OBJECTIVE

The efficacy of sarolaner was evaluated against ear mite infestation caused by Otodectes cynotis in dogs and compared with topical moxidectin/imidacloprid in a single-masked, multi-centre field study.

ANIMALS

Client-owned dogs with O. cynotis infestation were treated monthly with oral sarolaner (n = 163) or topical moxidectin/imidacloprid (n = 78).

METHODS

The presence of mites in the ear canals and the clinical signs associated with otoacariasis (including head shaking, pruritus/ear scratching, trauma or alopecia of the pinnae, and erythema, ulceration and debris in the ear canals) was evaluated on days 0, 14 and 30, and, if applicable, on day 60. Dogs were considered cured of mite infestation following one (on day 0) or two (on days 0 and 30) monthly treatments, if no live mites were found in either ear. Non-inferiority was evaluated at days 14 and 30.

RESULTS

Parasitological cure was achieved in 76.4%, 90.5% and 93.3% of the sarolaner-treated and in 53.9%, 63.5% and 66.7% of the moxidectin/imidacloprid-treated dogs on days 14, 30 and 60, respectively. At study completion, on day 60 at the latest, parasitological cure was achieved overall in 99.4% of sarolaner-treated and 87.8% of moxidectin/imidacloprid-treated cases. The parasitological cure rate for sarolaner was non-inferior to moxidectin/imidacloprid at days 14 and 30. The clinical signs of otoacariasis improved throughout the study in both groups. There were no treatment-related adverse events.

CONCLUSIONS

A single oral administration of sarolaner was safe and highly effective in the treatment of O. cynotis infestation in dogs.

Assessment of the insecticidal activity of afoxolaner against Aedes aegypti in dogs treated with NexGard®

Twelve healthy dogs were studied in this parallel group, blinded, randomised, and negative controlled efficacy study. On Day -1, the 12 dogs included were ranked within sex in descending order of individual pre-treatment (Day -5) fed mosquito counts and randomly allocated by blocks of two dogs to the untreated control group or the afoxolaner-treated group. NexGard^® (Merial, now part of Boehringer Ingelheim Animal Health) was administered orally on Day 0 in accordance with the European label instructions. On Days 1, 7, 14, 21 and 28, all dogs were exposed for a duration of 1 hour to 50 ± 5 unfed Aedes aegypti females. After each exposure, mosquitoes were collected after 1 hour and assessed for viability during collection and at 24 ± 2 hours. The arithmetic (and geometric) mean values of live fed mosquito counts at 24 hours after the exposure periods for the negative control group ranged from 33.7 (32.3) to 49.8 (49.7), indicating that this was a vigorous mosquito strain. There was no significant difference between control and treated groups in the number of live and fed mosquitoes at each 1 hour post-exposure collection time. Based on arithmetic and geometric mean values at 24 hours after each exposure, significantly fewer live fed mosquitoes were recorded in the treated group, compared to the negative control group, throughout the study (p < 0.001). The afoxolaner insecticidal efficacy against A. aegypti varied from 98% (Day 2) to 75.3% (Day 29) based on arithmetic means, and 98.7% (Day 2) to 89.8% (Day 29) based on geometric means.