
I have used the Spray for years and have never had any fleas. My oldest is flea alergic and used to get Hot spots because of this in the summer.
She has some for the first time this eyar as I weas late frontlining them in the spring and did them with the Spot on in May, I don't think the spot on is as effective, but have always found the spray to be so, so much so that I no longer bother with a household spray.
Do you have Cats. if so I suggest that they need doing and the house with one of the sprays that sterilises the fleas in the environment. Once this is doen the Frontline will work fine on the dogs. It does say it kills most of the fleas within 24 hours, so if tey are being reinfected you will see live fleas.