K9 Advantix II Flea, Tick & Mosquito Topical Treatment for Large Dogs (21–55 lbs)

K9 Advantix II Large Dog | 5-Way Protection: Fleas, Ticks, Mosquitoes & More

Quick Facts:

• Best for: Large dogs, 21–55 lbs
• Main active ingredients: Imidacloprid & Permethrin
• Format: Topical monthly applicator, 1- to 6-month supply packs
• Key support: Kills & repels fleas, ticks, mosquitoes, biting flies & lice
• Prescription status: Not required — available over-the-counter
• Ideal for: Dogs frequently outdoors, especially in mosquito-heavy areas (dogs only — never use on cats)

Description: K9 Advantix II distinguishes itself from many competing topicals by targeting five pests in one formula — fleas, ticks, mosquitoes, biting flies, and lice — and by repelling as well as killing, rather than only killing on contact. Applied along the back of a large dog (21–55 lbs) from shoulders to tail base, the treatment starts killing fleas within 12 hours of the first application, and because it repels rather than simply waits for a bite, it's specifically positioned to reduce a dog's exposure to mosquito-borne and tick-borne diseases before they can even bite. The formula continues working for up to four weeks per application, breaking the flea life cycle by killing adult fleas before they can lay new eggs. It's an easy-to-apply topical rather than a pill, which some owners prefer for dogs that are difficult to medicate orally. One critical safety note that applies to this entire product line: K9 Advantix II is formulated specifically for dogs and must never be used on cats, since one of its active ingredients (permethrin) is toxic to felines — a detail that should be prominently featured on any product page selling this item, especially in multi-pet households.