The present invention relates to a device for applying a liquid pesticidal formulation to an external surface of a domestic animal, the device comprising an inlet and a plurality of spaced apart outlets, wherein the device is adapted such that when the middle of the device is positioned substantially above the spine of the animal, at least one outlet is positioned substantially above each flank of the animal. The invention also relates to a method for the treatment or prophylaxis of parasitic infestations, including ectoparasitic and/or endoparasitic infestations, of domestic animals comprising topically administering to said animal a pour-on pesticidal formulation to a region of the external surface of an animal extending from one flank to the opposing flank.