Yes, heartworms are nearly 100% preventable in animals, including household pets like dogs and cats. Veterinarians offer medications designed to prevent heartworms in pets, giving you peace of mind in knowing your pet is protected. Yes, heartworms are nearly 100% preventable in animals, including household pets like dogs and cats. Veterinarians offer medications designed to prevent heartworms in pets, giving you peace of mind in knowing your pet is protected.