The Liberty 50 for Puppies, Miniature & Toy Dogs with sunlight-stable Nylar IGR kills more Fleas, Ticks, Mosquitoes, Lice and Mites than leading Spot-on treatments! Liberty 50 not only kills, but repels and prevents re-infestation of pests for up to 8 weeks. Liberty's active, Permethrin is known to be one of the safest on the market - in fact if you check any of the Spot-On Websites, you won't find Star Horses products (Freedom 45) listed as having any negative reactions.