Efficacy of imidacloprid on dogs and cats with natural infestations of fleas, with special emphasis on flea hypersensitivity.

In this study the efficacy of a 10% weight per volume solution of imidacloprid--registered as a flea control agent with the trademark Advantage topical solution--was assessed in Italy under field conditions in a total of 3272 dogs and cats. During the 4-week trial the number of fleas on each animal was assessed and lesions of flea allergy dermatitis (FAD; i.e., miliary or maculopapular dermatitis, hyperpigmentation, and crusty thickenings of the skin), alopecia, and pruritus were evaluated. Imidacloprid had a notable adulticidal effect and residual activity that controlled fleas and prevented reinfestation of treated animals for at least 4 weeks. In addition, a significant decrease of the clinical signs was documented regardless of each animal's breed, sex, body size, haircoat length, and living conditions. Some of the dogs were washed or shampooed after treatment without showing statistical differences in efficacy. This study demonstrates that a single treatment with imidacloprid is able to effectively control flea infestations in dogs and cats for at least 28 days and significantly contributes to the improvement or disappearance of clinical signs of FAD.