Listen to wvvet he has never steered anyone wrong on this. I have used Frontline on my lab and chessie the last 4 years and I have never seen a tick stay either one and fleas, flies, and mosquitos all seem to leave them alone. They usually go for a swim a couple times a week and it does not seem to make any difference. The pests just don't bother them anymore. My pasture is crawling with ticks and whenever I take them for a walk I come home and have to pick ticks off of me maybe I'll try Frontline on myself next month.