The most common parasites you can find on your cats or dogs are fleas. These parasites can make their way into your home through an open window, a crack in the door, your pets, or you, without even knowing it. Fleas can really be irritating and annoying for your cat or dog. They cause itching, hair loss, general discomfort, which can lead to worms and even diseases. The worst part of a flea infestation is what you can’t see: flea eggs and larvae, which can keep the flea infestation cycle going. CrossBlock is indicated for the prevention and treatment of flea infestations on cats and dogs. CrossBlock kills fleas before they lay eggs and keeps killing fleas for a full month, as well as their eggs and larvae. CrossBlock is a waterproof topical solution for cats and dogs