The present invention relates to a liquid topical veterinary pharmaceutical composition consisting of fipronil, permethrin at high concentration and pyriproxyfen such that it does not crystallize when it is applied to the coat of an animal, and to the use thereof in the prevention and/or treatment of infestations of domestic animals by external parasites. The present invention also relates to the use of pyriproxyfen as an inhibitor of the crystallization of a liquid formulation comprising fipronil and permethrin at high concentration.
