Efficacy of an amitraz-impregnated collar in preventing transmission of Borrelia burgdorferi by adult Ixodes scapularis to dogs

Objective-To determine whether an amitraz-impregnated collar could prevent transmission of Borrelia burgdorferi by Ixodes scapularis to dogs. Design-Laboratory trial. Animals-8 specific-pathogen-free Beagles. Procedure-On days -15 and -1, all dogs had negative ELISA results for serum antibodies against B burgdorferi. On day 0, 4 dogs were each fitted with a n amitraz-impregnated (9%) collar, and 4 dogs served as untreated controls. On day 7, all dogs were infested with 100 / scapularis (approx 50 females and 50 males) with a known B burgdorferi infectivity rate of 39.4%. On days 21, 28, 35, 42, 56, 70, and 84, each dog was tested for serum antibodies a gainst B burgdorferi via ELISA and a western blot technique. Additional ELI SA were also performed for serum antibodies against antigenically similar o rganisms. Results-By day 70, all control dogs had developed serum ELISA responses ran ging from 328 to 510 kinetics-ELISA units (equivalent to end-point titers o f approx 43,500 to 60,000), whereas treated dogs remained seronegative thro ughout the study. Western blot assays performed on all serum samples confir med that antibodies detected in control dogs reflected responses to specifi c antigens of B burgdorferi, whereas treated dogs had no such antibodies. A dditional serologic analyses confirmed that antibody responses observed in control dogs were not attributable to antigenically similar organisms. Conclusions and Clinical Relevance-Amitraz-impregnated collars prevented tr ansmission of B burgdorferi in 4 of 4 treated dogs and may be a useful mana gement tool for prevention of borreliosis in dogs.