Depending on the size of your pet dog you can give him a half clove of garlic a week and he won't get fleas again.

 I have found that a 3 phase method works best. Treat the dog with a once-a-month topical flea treatment such as Advantage or Advantix(this is a liquid applied behind the neck so they can't lick it off). Then you should treat your home with flea bombs if the infestation is indoors as well. Also your yard needs to be treated too with something like Diazanon or your dog will just carry them back inside with him. I have 2 dogs & 3 cats that are all indoor/outdoor & have stayed flea-free using the above method.(prior to doing the 3-step method. I had major flea infestations as well) But no more. Good Luck!!