Well, dogs have a big advantage over children. By the time they enter their teens, they generally become docile, loving, peaceful and then die. Harsh perhaps, but undeniable.
One big difference is that pets won't be around to cook your dinner, wipe your ass for you, and help upkeep your house(if your still have one) when you're 85 years old and unable to do so yourself.
My dogs are the best alarm protection I can have.
NO ONE gets within a 1/4 mile of my property without one of them telling me so.