Frontline Top Spot for Cats is a monthly topical spot-on treatment for all breeds of cats. The spot-on treatment prevents fleas, flea life cycles, flea infestation and biting lice on cats. The long-lasting treatment remains effective for a period of 4 weeks and prevents parasitic re-infestation. Frontline top spot for cats contains an active ingredient Fipronil which attacks the central nervous system of the fleas thereby killing them with the insecticidal property before they can bite the cat. This rapid-acting treatment kills fleas 24 hours of application.