Efficacy of an imidacloprid/flumethrin collar against fleas and ticks on cats

BACKGROUND: The objectives of the studies listed here were to ascertain the therapeutic and sustained efficacy of 10% imidacloprid (w/w) and 4.5% flumethrin (w/w) incorporated in a slow-release matrix collar, against laboratory-infestations of fleas and ticks on cats. Efficacy was evaluated against the flea Ctenocephalides felis felis, and the ticks Ixodes ricinus, Amblyomma americanum and Rhipicephalus turanicus. The number of studies was so large that only a general overview can be presented in this abstract. METHODS: Preventive efficacy was evaluated by infesting groups of cats (n = 8-10) with C. felis felis and/or I. ricinus, A. americanum or R. turanicus at monthly intervals at least, for a period of up to 8 months. Efficacy against fleas was evaluated 24 to 48 h after treatment and 24 h after infestation, and against ticks at 6 h (repellent) or 48 h (acaricidal) after infestation. Efficacy against flea larvae was evaluated over a period of 8 months by incubating viable flea eggs on blanket samples after cat contact. In all cases efficacy was calculated by comparison with untreated negative control groups. RESULTS: Efficacy against fleas (24 h) generally exceeded 95% until study termination. In vitro efficacy against flea larvae exceeded 92% until Day 90 and then declined to 67% at the conclusion of the study on Day 230. Sustained acaricidal (48 h) efficacy over a period of eight months was consistently 100% against I. ricinus from Day 2 after treatment, 100% against A. americanum, except for 98.5% and 97.7% at two time-points, and between 94% and 100% against R. turanicus. From Day 2 until 8 months after treatment the repellent (6 h), efficacy was consistently 100% against I. ricinus, and between 54.8% and 85.4% against R. turanicus. CONCLUSION: The rapid insecticidal and acaricidal properties of the medicated collars against newly- acquired infestations of fleas and ticks and their sustained high levels of preventive efficacy have been clearly demonstrated. Taking into account the seasonality of fleas and ticks, the collars have the potential to prevent the transmission of vector-borne diseases and other conditions directly associated with infestation throughout the season of parasite abundance.