When I started using it my dogs didn't have fleas or tick either. I was using it as a preventitive to and then they all got fleas and ticks by the thousands. I was a really bad infestation. I was really upset and continued to use the product and treat house, dog, yard, vehicle for the infestation when I finally got it under control the stuff still wasn't helping on my dogs. I have gone back to using the k-9 advantix (although Kitty still has some fleas and ticks after using that for the last 2 months.)
