In most cases dogs can be a secondary security system as long as they will bark when necessary to give a warning. Dogs can scare a stranger away by either barking or looking fierce. But remember that they can be lured away, poisoned, killed, or even stolen. Trained attack dogs are not recommended because the risk of liability to the owner is great should the dog attack an innocent person. Outside dogs should be kept in a fenced area with a good lock on the gate.