Efficacy of a novel topical combination of fipronil, (S)-methoprene, eprinomectin and praziquantel against adult and larval stages of Toxocara cati in cats

Abstract The efficacy of a novel topical combination of fipronil 8.3% (w/v), (S)-methoprene 10% (w/v), eprinomectin 0.4% (w/v), and praziquantel 8.3% (w/v) (BROADLINE ® , Merial) was evaluated against adult and larval Toxocara cati in four controlled studies. All studies included experimentally infected, purpose-bred, short-haired cats. In two studies, 22 or 20 cats harbouring patent infections as confirmed by pre-treatment faecal examination, were included. Within each study, cats were allocated to one of two groups: control or treated. In a further two studies, 30 cats were included in each; cats were allocated to one of three groups: control, treated when T. cati were expected to be either migrating third and/or fourth-stage larvae, or treated when T. cati were expected to be fourth-stage larvae. Cats allocated to the treated groups received a single topical application of the combination product at 0.12 mL/kg bodyweight (10 mg fipronil + 12 mg (S)-methoprene + 0.5 mg eprinomectin + 10 mg praziquantel per kg). For parasite recovery and count, cats were euthanized humanely at different intervals after treatment. In the studies targeting adult T. cati , ascarids were recovered from all controls (range 1–150) while only two worms were isolated from one treated cat. Thus, the efficacy of the novel combination was 99.4% and 100% against adult T. cati . For studies targeting larval T. cati , up to 21 worms were recovered from each of seven or eight of the control cats per study. No T. cati were recovered from the treated cats in two studies, corresponding to 100% efficacy against both, migrating third and/or fourth-stage larvae and luminal fourth-stage larvae. All cats accepted the treatment well and no adverse experiences or other health problems were observed throughout the studies.