Elanco Advantage II Topical Flea Treatment & Prevention for Dogs 6-Month Supply SM Dogs (3-10 lbs)K9 Advantix kills and repels fleas, ticks, mosquitoes, biting flies and lice. Simpler than a flea collar and hard to swallow pills, this topical formula works within 12 hours of initial application to stop existing flea infestations on dogs and prevent new ones by killing adult fleas on contact before they lay new eggs or bite your dog. K9 Advantix offers fast relief at an excellent value, so you and your dog can get back to the things you love most.