Vetsupply: For controlling fleas and heavy flea infestation, Advantage for dogs is an excellent pet product. This spot-on is highly effective in killing adult fleas and larvae on dogs and their surroundings. It affects re-infesting fleas within 3 to 5 minutes, kills re-infesting adult fleas within 1 hour and flea larvae in your dog\'s surroundings within 20 minutes of contact with the active ingredient.