K9 Advantix II is a veterinarian-recommended topical flea and tick treatment designed for small dogs weighing 4 to 10 pounds. This Costco value pack includes two 4-dose boxes for a total 8-month supply of protection. The formula defends against five common pests: fleas, ticks, mosquitoes, biting flies, and lice.

The treatment begins killing fleas within 12 hours of initial application and continues working for a full 30 days per dose. Fleas and ticks are killed on contact, meaning they do not need to bite your dog to die. The active ingredients include Imidacloprid (8.80%), Permethrin (44.00%), and Pyriproxyfen (0.44%), an insect growth regulator that prevents flea eggs and larvae from developing.

The topical spot-on formula is easy to apply by dispensing evenly along the top of the back from the shoulder to the base of the tail. It is fragrance-free and waterproof 24 hours after application. Dogs must be at least 7 weeks old and weigh between 4 and 10 pounds. No prescription is required. Do not use on cats.