not containable

Question
I have a 3yr old male lab (not neutered) that we have had since he was 6 weeks old. Within the last few months he has started he has started jumping the four foot fence in the back yard. I can call him and he will jump right back in; However, it is causing issues with my neighbor and their dogs. They have one female and my dogs likes to go "visit her" and then they have a male. My dog doesn't seem to jump the fence every time he sees the male, but if that dogs gets too close to the fence he will jump and they end up in a fight.
Any suggestions? I am afraid that he is going to get hurt in a dog fight, or hit by a car! Do you think neutering would help?

Answer
Neutering often makes a big difference.  I see no reason not to try it.  You frequently have problems beginning up to 3 years old when the dog finally matures.  They will then continue established behaviors without major efforts to change them.  

Neutering may not be enough now.  If he is using his front legs to pull himself over the fence, "Coyote Rollers" should help.  I don't have a link, but they should show up in a search.  If he is making a clear jump, I don't think they would work.