I use Frontline now. Yes it cost more but according to my Vet, it works. I also asked him why some of the other brands were so much cheaper and he said because they really do not work all that well. Some of the other brands will wash off or wear off real easy. Frontline on the other hand hangs in there according to him.

Last year my dog came down with Lymes Disease. He had been vaccinated with his Lymes shot, and had Harts Flea and Tick juice on him like directed.. I thought he was safe. Well I was wrong. Due to the old fellow's age he has not been able to shake the lymes, so now he is becoming arthritic, his back hips are going out, he seems very uncomfortable at times, and is on a Rimadyl twice a day for the arthritis. One of these days the Rimadyl will not be enough to keep him comfortable and there is a risk of liver damage from the Rimadyl. Then I will be faced with that terrible decision.....

Check with your vet and make sure your pet is protected.