The treatment and prevention of flea and tick infestations in cats and dogs, and as part of a treatment strategy for Flea Allergy Dermatitis in cats and dogs. The product is active against Ixodes spp. including Ixodes ricinis, important as the vector of Lyme disease. The product controls infestations with Trichodectes canis biting lice on dogs and Felicola subrostratus biting lice on cats.