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

Abstract
Objective—To determine whether an amitraz-impregnated collar could prevent transmission ofBorrelia burgdorferibyIxodes scapularisto 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 againstB burgdorferi. On day 0, 4 dogs were each fitted with an amitraz-impregnated (9%) collar, and 4 dogs served as untreated controls. On day 7, all dogs were infested with 100I scapularis(approx 50 females and 50 males) with a knownB burgdorferiinfectivity rate of 39.4%. On days 21, 28, 35, 42, 56, 70, and 84, each dog was tested for serum antibodies againstB burgdorferivia ELISA and a western blot technique. Additional ELISA were also performed for serum antibodies against antigenically similar organisms.Results—By day 70, all control dogs had developed serum ELISA responses ranging from 328 to 510 kinetics-ELISA units (equivalent to end-point titers of approx 43,500 to 60,000), whereas treated dogs remained seronegative throughout the study. Western blot assays performed on all serum samples confirmed that antibodies detected in control dogs reflected responses to specific antigens ofB burgdorferi, whereas treated dogs had no such antibodies. Additional serologic analyses confirmed that antibody responses observed in control dogs were not attributable to antigenically similar organisms.Conclusions and Clinical Relevance—Amitrazimpregnated collars prevented transmission ofB burgdorferiin 4 of 4 treated dogs and may be a useful management tool for prevention of borreliosis in dogs. (J Am Vet Med Assoc2001;219:185–189)