My sister got bitten in the face once (thankfully no scars) by an aggressive Rottweiler. Here's how the story went:
Mom took my sister to a drug dealer's house in 1987 and left my sister outside the front yard inside the fence and went inside. Next thing my mother heard was screaming from my sister and she ran outside, seeing the dog over my sister with his mouth on her face. Needless to say, mom took my sister away from the dog and went home.
That afternoon, dad came home and found out what happened to his daughter. Boy, he was pissed off, both at my mother and at the drug dealer. So he jumped into his pick up truck, drove out to the drug dealer's house and walked up to the fence. Right away, the dog ran barking at dad loudly and dad pulled out his gun and shot the dog point blank, instantly killing it. The drug dealer heard the gun shot and ran out the door shouting "What do YOU think you're doing!?"
Dad pointed the gun at the man saying, "That dog bit my daughter. As for you, I suggest you leave town tonight and never come back. Or I will come and I will find you."
The man left town and never came back.