I use frontline on all my other dogs and the do not have fleas. Barney was treated with frontline and he still has fleas. I have used comfortis on him bombed my house and every night I go over with him with a flea comb so and kill all the fleas I can get in 1/2 hour. He is not infested but I am still getting fleas off of him and the fleas are all at different stages in their life. He was does 2 weeks ago with frontline so I am nervous to dose him with something else again. Does anyone have any advice on what they would do. the fleas are visible last time a woman saw one on him in town and flipped out about it. I am going to a dog show in pennsylvania next week so I was hoping that I could get rid of them by then.