Both my labs have been attacked, My bitch lab- the first dog was a terrier cross, and the one that really done it was a Boxer, she did have injuries. I have been working with her fear aggression, she is loads better, and mixes loads better, but doesn't do in your face type dogs.
My male lab has been attacked by a pack of Lurchers, the owners were incredibly ignorant, i have heard of a recent incident involving these dogs, even after reporting it to the Warden
Also two black Labs laid into him, while we were innocently walking past their house. Luckily he has no lasting effects

Every time this has happened, it really could have been avoided, if the owners were a little more responsible.