Establishment of the cat flea (Ctenocephalides felis felis) on the ferret (Mustela putorius furo) and its control with imidacloprid

As the ferret, Mustela putorius furo L. (Carnivora: Mustelidae), is becomin g increasingly popular as a pet animal and as it is susceptible to the cat- flea. Ctenocephalides felis felis Bouche (Siphonaptera: Pulicidae), an expe rimental model was established for evaluating insecticidal treatments on th is host. A high establishment rate (76.7-91.8%) was recorded when 60 unfed adult C. felis were placed on ferrets. This provided an adequate infestatio n for chemotherapeutic evaluation without causing undue discomfort to the h ost. Twelve ferrets were allocated to two groups matched for sex and indivi dual ability to sustain a flea population. One group was treated topically with an imidacloprid spot-on formulation at a dose rate of 10 mg/kg body-we ight on Day 0. All ferrets were infested with C. felis on Days -1, 7, 14, 2 1 and 28, amd flea counts were performed 8 and 24 h post-treatment and one day after each subsequent infestation. Fleas were removed at all but the 8h count (when they were returned to their host). Flea burdens were reduced b y 95.3% (P < 0.001) within 8 h of treatment and 100% efficacy was recorded at 24 h. At 1, 2, 3 and 4 weeks post-treatment, protection against re-infes tation was 92.9% (P < 0.001), 55.7% (P < 0.02), 18.3% (NS) and 7.4% (NS), r espectively. Thus, at this dose rate, imidacloprid gave excellent efficacy against a resident C. felis population and provided a high level of residua l activity for at least one week after treatment.