We use Frontline Plus and last fall Rocky had a tick on his head. I called the vet after I got it out, it was dead, and he said that the tick probably didn't die until it bit him. I, being the crazed yorkie mom that i am, took him to the vet to have Dr M look at the bite area. He said that the Flea and Tick applications don't stop them from getting on the dog, it kills them after they bite. I hope it was just a one time thing and those buggies don't get on my babies.Gross.