Keep those bloodsuckers at bay with Sentry FiproGuard Flea & Tick Spot Treatment for Dogs. This fast-acting flea treatment is waterproof and kills flea eggs and larvae for up to twelve weeks. With Fipronil as the active ingredient, Fiproguard is a trusted, effective way to kill adult fleas and ticks. Plus, this treatment protects your dog against chewing lice as well so your furball can focus on spending time on fun and play, and spend less time focused on fleas.