We have two little dogs. Chipper, who is my older Yorkie-Poo, and Miss Tootsie, who is a heeler mix. Tootsie looks like across between a Queensland Blue Heeler and either a small Fox Terrier, or maybe a Chihuahua. Regardless, she thinks that she is the official Guard Dog for the family.
The other night, we were sitting in the house with the front door open, when Tootsie started barking ferociously and ran out the door. When my husband got there (right behind her), there were two huge German Shepards that came right up on the porch, and would probably have run right into the house if Miss Tootsie had not been out there barking at them. She was not afraid at all, and was doing her job as the family guard dog, all 10 lbs of her !