Use of injectable lufenuron for treatment of infestations of Ctenocephalides felis in cats.

To determine whether and for how long a single dose of a new injectable formulation of lufenuron would successfully control experimentally induced Ctenocephalides felis infestations in cats. 15 cats (3 groups of 5). Each group of cats was housed in a separate room. Each cat was infested with 150 fleas, and flea counts were checked weekly. Once flea populations had stabilized, cats were treated with lufenuron at a dosage of 5 mg/kg of body weight, s.c. (group 1) or 10 mg/kg, s.c. (group 2). Group-3 cats were not treated. Flea counts were checked weekly for 18 weeks, and effectiveness was determined by comparing flea counts for treated cats with flea counts for control cats. Cats were reinfested with fleas during weeks 19, 26, 36, and 49, and flea counts were again determined weekly. Effectiveness for both dosages of lufenuron was > 90% by 5 weeks after treatment, > 95% by 9 weeks after treatment, and > 98% by 13 weeks after treatment. Reinfestations performed during weeks 19 and 26 were well controlled (ie, > 90% reduction in flea counts, compared with control group) in both groups of cats treated with lufenuron. Reinfestations performed during week 36 were well controlled only in cats treated with lufenuron at the higher dosage. Reinfestations performed during week 49 were not controlled in either group of treated cats. A single dose of the new injectable formulation of lufenuron should control flea populations in cats for up to 26 weeks, even among cats that are periodically reinfested with fleas.