The use of a pour-on and spray dip containing Amitraz to control ticks (Acari: Ixodidae) on cattle

Knockdown and persistence efficacies of a pour-on containing Amitraz 1% and Cypermethrin 1% and a spray dip containing 12.5% Amitraz were compared. Knock-down and persistence efficacies of the Amitraz spray dip against Rhipicephalus (Boophilus) decoloratus and Amblyomma hebraeum were significantly higher for the duration of the trial than those of the pour-on. In the case of Rhipicephalus appediculatus and Rhipicephalus evertsi evertsi, efficacy was significantly higher on Days 2 and 5. Resistance testing prior to the start of the trial indicated that R. (B.) decoloratus was resistant to both Cypermethrin and Amitraz, yet in the case of the spray dip excellent efficacy results were obtained. It is thought that the cattle's scruffy winter coat may have hindered the spread of the pour-on, but that the thorough wetting and especially the higher concentration of active ingredient applied via the spray dip allowed this formulation to be effective. These results show that under certain conditions a spray dip containing 12.5% Amitraz may be more effective than a pour-on containing 1% Amitraz and 1% Cypermethrin, despite apparent in vitro resistance.