biting

Question
My golden will be 4 next month.  we use an electric fence which he does go through on occasion(1X a month) if something on the otherside is i guess worth it.  2 weeks ago he went through and attacked an autistic man that was walking past.  he bit him 2x.  what would have caused this behavior?   he has never bitten anyone before but has on occasion growled at people.

Answer
Dogs can sense things such as autisticism.  Usually they do not react aggressively, but how the man reacted to him could be part of the cause.  

I don't think this is a problem you can train the dog out of.  I do recommend obedience training if you haven't and also neutering him.  The trend is toward earlier neutering.  

You may have to give up on the electric fence and put up a conventional one.  The electric fences are great, but don't work with some dogs.