Advantage Multi Topical Solution is a broad-spectrum once a month topical application that treats and controls fleas, prevents heartworm disease and treats heartworm microfilaria, treats and controls hookworms, roundworms and treats and controls ear mites in cats. Advantage Multi 9 Topical Solution is also used for the prevention of heartworm disease and treatment and control of fleas in ferrets weighing at least 2 pounds.