Do you keep your dogs in or out?
If they have fleas you will need to treat their sleeping quarters too and if they are kept in the house then the whole house will need treating .
Fleas seem to have been rife this year and I have used everything (Frontline and Bob Martin spot on, bathed a few times with Vetzyme medicated shampoo, combed with flea combs several times, Bob Martin spray for pet & home, Bob Martin flea kill and now have them with permanent flea collars on) . Not sure which treatment worked but they haven't had any more on them .