I am no expert , but I would be VERY cautous about using a fogger with kitties in the house. A flea comb is an inexpensive 'fix' for getting the fleas off of the animals themselves, but you are right if the house and yard are infested you need something more agressive. Hopefully another PT'er with more knowledge in this area will offer some advice. Best wishes to you and the kitties Maybe call a vets office for some general advice.