Advantage for extra large dogs is a special and easy to use monthly spot-on for the treatment and prevention of fleas on dogs. This quick action stops flea bites within 5 minutes and re-infesting adult fleas within 1 hour of administration. Destroying fleas, it prevents further flea infestation for a month. The waterproof flea preventive remains intact with the dog's body and protects against flea infestation. Browse our wide range of flea and tick products online at DiscountPetCare with free shipping.