Hi charlotte, First off, would i be right in saying you keep the dogs in the house? If yes, although frontline is very good, if you are regularly getting re-infestation then i would suggest that you go to your vet/pet shop and try to get something like ARDAP. This you will use to spay all soft furnishing that the dogs come in contact with, carpets, perticularly near the skirting boards and also the furniture, this is where fleas will very often lay their eggs. The dogs bedding must be put through on a hot wash if possible, dont forgett as so many people do to treat the car. Obviously the d