Dogs are really marvelous creatures on earth and can make possible several things that you can never imagine. They are more intelligent than your idea. Most of the watch dogs are cultivated through breeding and cross breeding for special purposes. They are truly faithful creature that will die for saving your life. If cared and maintained properly they can be your best friend.
That is why dog are trained in police force. But in force Retriever dogs are brought up and trained to work with them. You must have noticed that cops always address them as their partner instead of their pets. Dogs look for a leader and companion whom he can follow and take orders from. Do not decide a dog’s capability by its size. There are many instances which will change your idea about watch dogs.
You must have seen the little dog called Chihuahua. Well, it is a very good watch dog though it weighs up to only 2 pounds perhaps. It does not think about its own size rather tend to have a personality suitable for a German shepherd. It is very vocal while guarding the house. A Chihuahua needs proper training and socialization so that it does not become a little angry snapping dog. To most children they are not so good companions. They are very intelligent but easily get bore and destructive. Do not let their small size to fool you.