This study was conducted following Good Clinical Practices, VICH Guideline 9 , Guideline on Statistical Principles for Veterinary Clinical Trials , and Guideline for the Demonstration of Efficacy of Ectoparasiticides . All dog owners provided informed consent following written and oral explanation of the study objectives and treatments. Seven veterinary practices across Albania, Poland, Spain, Germany and Portugal enrolled client-owned dogs presented with generalized demodicosis.
Enrollment of dogs
Generalized demodicosis was diagnosed by the presence of more than four affected skin areas with lesion diameter >2.5 cm or pododemodicosis in at least one paw; with positive skin scrapings (≥3 Demodex spp mites). Dogs were at least 8 weeks old and weighed at least 2.0 kg. Dogs needing intensive care, or that were treated with injectable corticosteroids in the past 30 days were excluded. Any ongoing treatment with oral or topical corticosteroids had to be discontinued before inclusion in the study. Dogs were excluded if treated with: fluralaner in the previous 3 months; other isoxazoline products within 35 days; macrocyclic lactone parasiticides, except at approved heartworm prevention doses, within 30 days; amitraz, fipronil, pyriproxyfen, metaflumizone, pyrethrins, deltamethrin or permethrin, within 30 days; or shorter-acting products with miticidal activity within 14 days. Treatment of enrolled dogs with corticosteroids, immunosuppressants (cyclosporine, oclacitinib) or with any product having miticidal activity was not permitted during the study, and owners were instructed to avoid using in-house or on-property acaricides and to avoid shampooing the study dog during the 3 days following each treatment. Each owner was also instructed to observe their dog for any unfavourable or unexpected events and to report any observations to the study clinic. Enrolled dogs were maintained in their home environment throughout the study, and owners returned their dog to the clinic on days 28, 56 and 84.
Qualifying dogs enrolled in each clinic were randomly allocated to either a fluralaner group (oral or topical) or to a topical imidacloprid-moxidectin group. The study enrolment target was 50 dogs in each fluralaner group and 25 dogs in the imidacloprid - moxidectin group. Dogs in this group with mild to moderate demodicosis were treated every 4 weeks, while severely affected dogs had an increased treatment frequency to once per week, at the discretion of the dispensing veterinarian. All products were administered according to the product prescribing information directions.
ogs in one fluralaner group received a single oral fluralaner chewable tablet (Bravecto® chewable tablets, MSD Animal Health) administered at the label dose rate of 25-56 mg/kg. These dogs were fed within one hour of treatment and observed for 10 minutes after treatment to verify that the tablets were retained. In the other fluralaner group, dogs received a single topical 28% w/v fluralaner application (Bravecto® Spot-On Solution, MSD Animal Health), at the label dose rate of 25-56 mg/kg. Dogs in the imidacloprid -moxidectin group received multiple sequential administrations of at least 10mg/kg imidacloprid and 2.5 mg moxidectin (Advocate® for Dogs, Bayer). Dogs in this group with mild to moderate demodicosis were treated every 4 weeks while severely affected dogs had an increased treatment frequency to once per week at the discretion of the dispensing veterinarian. Fluralaner treatment and the initial imidacloprid-moxidectin treatment were administered on day 0.
When clinical signs of Demodex-associated pyoderma were observed, study dogs received antibiotics or topical antiseptics at the discretion of the attending veterinarian.
Assessments of demodicosis
At each scheduled visit, deep skin scrapings for Demodex mites were made at five different skin areas, each skin scarping approximately 1 cm2. Where necessary (e.g. long or medium-haired dog), hair was removed at the area to be scraped, and the skin was firmly squeezed prior to and during scraping to eject mites from hair follicles . Scrapings were made in the direction of hair growth with a blade or spatula covered with mineral oil until capillary oozing was observed. Hairs were plucked from affected areas where obtaining a scraping was difficult (e.g. periocular and interdigital areas). Efforts were made to scrape the same affected areas at all assessments, unless those areas appeared normal and other active lesions were present. The collected material was transferred to a slide, mixed with mineral oil, placed under a cover slip and examined under a microscope (4x or 10x objective) to count live mites (larvae, nymphs and adult stages) (eggs were not counted). Clinical signs and extent of demodectic lesions on each dog were assessed on the days on which scrapings were made. Dermatological signs of alopecia, erythema, crusts, scales and papules were assessed and graded absent, mild, moderate or severe and estimates made of the overall extent of skin lesions using a scale of 0 (no lesions), 1 – 9% of the body affected, 10 – 29%, 30 – 49%, and ≥50%.
Primary efficacy was determined for each study group using the percentage of dogs free of live mites at the last two evaluation time points, days 56 and 84. Treatment was considered efficacious if the percentage of animals that were free of live mites at both evaluation time points exceeded 90%. The percentage of dogs free of live mites was also calculated separately for each visit.
A descriptive analysis was performed for mite counts and skin lesions: the distribution of mite counts and the number of dogs free of skin lesions were determined at each visit, as well as the distribution of types and extent of skin lesions.