Control of fly strike dermatitis in dogs with a topically applied combination of imidacloprid and permethrin: a prospective open-label controlled clinical trial.

Background: A prospective clinical study evaluated the tolerance and the efficacy of a combination of imidacloprid (10%) and permethrin (50%) (ADVANTIX ^® : Bayer HC AH, France) applied topically as a spot-on, for the treatment of natural canine fly dermatitis due to Stomxys calcitrans. The study was an open-label controlled study and one-month follow-up.
Methods: Fifteen dogs, from the same animal kennel, with active pinnal lesions of fly dermatitis, received a single application of the solution on the cranium and the base of the ears on Day 0 (D0). Five dogs, from the same kennel, similarly affected, served as non-treated controls. No other therapeutical or hygienic measures were taken. Lesional score was based on extension, alopecia, crusts, scales, erosions/ulcers, loss of substance and lichenification, each assessed on a 0-4 scale. Evaluation was performed on D0, D14 and D30. Total lesion score reduction was calculated at each time point using the arithmetic mean of total lesion score according to Abbott's formula. Scores obtained on D14 and D30 were compared with the baseline obtained on D0.
Results: No adverse event was recorded. The lesion score ranged between 4-13 at D0 in all dogs. In control dogs, D0 mean (± SD) lesion score was 7 ± 1.4. Lesion scores were maintained on D14 (6.6 ± 3.4) and D30 (8.6 ± 5.4). In treated dogs, D0 mean lesion score was 9.9 ± 2.5. Lesion scores of the treated dogs were reduced by 59% on D14 (4.1 ± 2.8) and 80% on D30 (1.9 ± 1.5) (P < 0.05).
Conclusions: The combination imidacloprid-permethrin proved safe and helpful in the management of natural canine fly dermatitis. It could also be suggested as a preventive measure with a monthly application during the fly exposition phase.