Advantage Multi for dogs and cats not only kills adult fleas and treats flea infestations, it is also 100% effective at preventing heartworm disease. It also controls hookworm, roundworm and whipworm. Advantage Multi is the best solution for all your pet’s parasitic problems. Advantage Multi is safe and effective, when used topically as directed, for dogs and puppies at least seven weeks of age and weighs at least three pounds. Read more about heartworm disease.