Note that these dogs are NOT guard dogs, they’re watchdogs. A watchdog is different from a guard dog. A watchdog barks to alarm you. His job is to warn you whenever a stranger is in your property. On another hand, a guard dog is a dog that truly attacks or just looks intimidating to scare intruders away. None of the small dog breeds in the list below is a guard dogs, they only aren’t big enough and scary enough.
So don’t confuse the two, the list below is a listing of the best small watchdogs. If you want to train your small dog to become a watchdog they are good methods out there, here’s one here.