Help protect your precious pooch from parasitic pests and the potentially harmful diseases they can transmit with K9 Advantix II Flea & Tick Treatment for Medium Dogs. This broad-spectrum, veterinarian-recommended treatment is specifically formulated to repel and kill fleas, ticks and mosquitoes on contact with no painful biting required. It further kills all life stages of fleas to prevent re-infestation, and even kills lice while also repelling biting flies. The waterproof formula for puppies and dogs 7 weeks or older and weighing between 11 and 20 pounds continues working for up to four weeks, even after bathing or swimming.