Paul, Be sure that the dogs are a real threat before you shoot them. I
own german shepherds and they are docile pets.. But some people have
a bad image of GSD's and I believe a gun happy parent could be capable
of shooting them if they ever got out of the yard. Be a good neighbor
and try to locate the owners. Let them know that their dogs are
showing agression.

Just remember that these things can escalate out of control. The owner
of these dogs might be similarly armed.