I have a friendly boy. He gets on with dogs of all ages and sizes. He was attacked by two large boxers a couple of mutha ago. Now he seems to have fear aggression towards any boxer. We have seen two boxers since the attack and he reacts badly to them, heckles up and starts to fight which is totally out of character.
Hi Maui, welcome to the forum Yes, this is totally possible. We've got an article with more information about reactive behavior on our main site, which might be of interest to you.
Looks like Labs can easily distinguish breeds. My girl also hates German Shepherds. Hasn't been attached by one, but when she was around 18months old a very insistent young male GS tried humping her repeatedly and wouldn't take ''no'' for an answer (she wasn't in season). Ever since, she gets very reactive around GS dogs even if they are totally ignoring her.
I'm always very aware when we are out walking on leash and will promptly change direction if I see a GS coming towards us. If we are in an off leash area, I call her to me and ask her to sit calmly whilst holding her collar. These measures are gradually working, but we avoid confrontations as much as possible. I think that remaining calm myself is important so I am not transmitting anxiety to my girl.