Fleas are horrible. Even if you remove them from the pet, they're in the house waiting to reinfest. The frontline or advantage will break the cycle. If you have cats, they need the stuff, too. Walmart and Sam's club have some new brand that's the same as Advantage but about half the cost. With 3 dogs and 2 cats the lower price is wonderful. Even if you haven't seen any fleas you need to keep on with the stuff. You can bring fleas in on your feet and it starts over again.