I have a pair of cocker spaniels and live in southern Indiana where the fleas vacation. I do not shave them down and so they have full hairy skirt so flea control can be a problem.
I don't know what med you use but I use Comfortis tablets once a month and have not had a flea in over a year! I just love it.
My boy will just eat it, he eats anything, but the girl is picky. I have tried breaking it up for her and still nothing.
Being a nurse, I finally ground it up and mixed it with water and use a large eyedropper, like you use to give meds to small children. That does the trick for me! Hope everything works out for you.