Disclosed is a method for treating ectoparasites in a non-human mammal, the method comprising administering to the non-human mammal an effective amount of a composition consisting of 5-chloro-N-[2-[4-(2-ethoxyethyl)-2,3-dimethylphenoxy]ethyI]-6-ethyl-4-pyrimidinamine (pyrimidifen) or a salt thereof and wherein the ectoparasites are selected from Boophilus spp. Rhipicephalus spp. Dermacentor spp. Hyalomma spp. Amblyomma spp. Otobius spp. Ornithodoros spp. Damalinia spp. Bovicola spp, the order Diptera or Ctenocephalides spp (and particularly for treating ticks, cattle lice, flies and fleas), and wherein the non-human mammal is selected from the group consisting of livestock and domestic animals.
