Instead of getting at the dog, who is just doing
whats natural and doesn't know he's [censored] you
off, why don't you just put a note in your
neighbors mailbox telling him that you saw what
he allowed his dog to do on your lawn. Let him
know, in a nice way, that you would appreciate it
if he would either pick it up or do it somewhere
else in the future. This way you might avert a war. Who knows, you might get to know him and
like him. Don't blame the poor animal for the
owners mistakes.