No matter where you and your canine companion like to spend time together, Frontline Shield Flea & Tick Treatment for Dogs is formulated to help protect her from the threat of fleas and ticks. This 3-in-1 topical solution helps repel ticks that may transmit Lyme disease, and mosquitoes that may transmit heartworm disease. Each dose lasts for 30 days delivering the powerful protection your dog needs wherever her next ex-paw-dition may take her! This treatment is specially formulated for dogs who weigh 21-40 pounds.