My dog came back from the dog sitter two weeks ago and had his monthly flea treatment when it was due a couple of days later. He was licking his paws a lot and seemed distressed. Anyway a couple of days ago I noticed insects moving on him which I presume to be fleas. My other dog now also has them We have never had a problem with fleas before. I've treated them both again with Advantage but can still see them although lots of dead ones also. I'm not sure whether I should have treated them again so soon, some research seemed to suggest it was ok. I'm just worried still that 2 days later I can still see live ones, is this normal or are they resistant ? Any help / advice appreciated.