K9 Advantix II by Elanco is a monthly topical flea and tick treatment formulated for medium dogs weighing 11 to 20 pounds. This Costco pack provides an 8-month supply of individual applicators, offering significant savings compared to purchasing monthly doses separately.

Each monthly dose spreads across the dog's skin at the hair root level, delivering broad-spectrum protection against fleas, ticks, mosquitoes, chewing lice, and biting flies. The waterproof formula maintains effectiveness even after bathing or swimming, making it well-suited for active dogs that spend time outdoors. Fleas are killed within 12 hours of application, and new fleas from the surrounding environment are eliminated within 2 hours, breaking the flea life cycle by preventing eggs, larvae, and pupae from developing.

K9 Advantix II also targets American dog ticks, which can carry Rocky Mountain spotted fever, and deer ticks, which can transmit Lyme disease, helping reduce the risk of parasite-transmitted diseases. The fragrance-free formulation is gentle enough for dogs with sensitive skin and is approved for use on dogs and puppies 7 weeks of age and older. For households with cats, treated dogs should be kept separate for at least 12 hours after application until fully dry, as the active ingredients can be harmful to cats.