Certifect for Dogs 20- 40 Kg ( 45-88 lbs) is Merial's new long-lasting, monthly topical flea and tick preventative. It works just like Frontline Plus with the addition of amitraz, a powerful tick-killing ingredient. It kills ticks and adult fleas rapidly and destroys the flea life cycle by killing flea eggs and larvae as well. Most topical tick treatments can take 24-48 hours to kill ticks, but Certifect for Dogs begins killing ticks in 6 hours and kills up to 100% of ticks in 18 hours. Furthermore, it is the only topical tick product that forces ticks to detach from an infested host. Certifect for Dogs provides complete flea control by killing adult fleas and preventing development of all flea stages. It not only kills fleas and ticks rapidly, but it continues to protect dogs from fleas and ticks for a whole month - even when swimming or bathing. In addition, Certifect for Dogs kills chewing lice and can also be used to control chewing lice and sarcoptic mange infestations. Benefits: • Effective, monthly topical flea and tick preventative that works just like Frontline Plus • Begins killing ticks in 6 hours and kills up to 100% of ticks in 18 hours, including the Deer Tick which can carry Lyme disease • Kills adult fleas and destroys fleas' life cycle by killing flea eggs and larvae • Each application provides a sustained full month of protection • Kills chewing lice and aids in the control of chewing lice and sarcoptic mange infestations • Can be used on pregnant and lactating dogs • Waterproof