I had a Lab that for the 1st 2-3 years, he fuckin bit everyone, he loved us and the kids and never tried to turn on us, he was always protecting us when it happen ( in his mind), but friends, family, an intruder, all got at least one nip from him,usually on the ass,and most of the time it was the people walking in unanounced...after that he was always cool with them...( except the intruder )...but anyways, he's 13 now and the best watch dog I've ever had....there were times when I wanted to kill him, but almost everytime it was someone coming in the yard or house without warning, he was just protecting his space....and never a kid, just adults got it
Anyways, he's a great dog, he's laying on the couch next to me right now...and I sleep good at night knowing he's there.
I'm glad I didn't kill him. Good Luck