Sergeant's® Pronyl OTC™ for Dogs topical flea and tick treatment contains the same veterinarian-recommended active ingredient, fipronil, found in Frontline® brand products. The power of fipronil is maximized by adding a second active ingredient. The patent-pending combination of active ingredients starts to kill fleas and ticks in minutes, even faster than Frontline®. It works so fast, it stops re-infestation of fleas, ticks and chewing lice and maintains high efficacy for 30 days, protecting pets and homes.