Fleas on a dog

Ones anybody know of a way to keep fleas off of a dog? We have a small mixed breed dog. 12#'s that stays in the house almost all of the time. However she constantly gets fleas and I do not think she is getting them from inside the house since we never see them anywhere else. She goes outside on a leash three or so times a day to do her business and comes right back in. Every few days I find one or two on her.



We have bathed her on Blue Dawn dish washing liquid. That did not seem to stop them. We give her a Capstar every few days and within a very few days we find another flea.....



It is unreal to me how they get on her that often.