A novel spot-on formulation containing fipronil (Eliminall(®)/Exproline vet™) Spot-on Solution for Dogs, Pfizer Animal Health, registered and manufactured by Krka, d.d, Novo mesto) was evaluated in three laboratory studies to confirm efficacy against fleas, ticks and chewing lice on dogs for at least one month. Control of two laboratory strains of cat flea (Ctenocephalides felis), two tick species (Rhipicephalus sanguineus and Dermacentor reticulatus) and the chewing louse (Trichodectes canis) was evaluated. In all studies, dogs were randomly allocated to treatment groups and compared with untreated dogs. The studies also included a commercial, comparator product containing fipronil (Frontline(®) spot-on, Merial Limited). All treatments were applied to the skin at one spot between the scapulae on Day 0. In the studies, dogs were infested with fleas and/or ticks prior to treatment and then reinfested at weekly intervals for up to 8 weeks after treatment and evaluated for efficacy at 2 days (48 h) after treatment and each reinfestation. These studies confirmed that treatment with the novel fipronil spot-on at the proposed commercial dose rate rapidly reduced existing infestations of fleas, ticks and chewing lice on dogs. Treatment provided control of reinfesting fleas for up to 8 weeks, up to 4 weeks control of ticks, and control of chewing lice. Copyright © 2012 Elsevier B.V. All rights reserved.