Sorry to be so blunt, but you're a fool if you haven't called the authorities about this (or taken the matter into your own hands with that shovel late at night). Your neighbors dog has already demonstrated that it can jump your fence and attack in your yard and yet you're letting your young child and your own pet out in your yard and hoping nothing happens? You don't want to risk offending your neighbors by calling animal control but you're willing to risk you son's life instead? Lord protect your dear child from your neighbors dog and from his negligent parents.
When our daughtwer was little she was attacked by a doberman. The owners kept the dog chained to a tree no doghouse and no fence. The dog whined and barked non stop. When the man left for work his wife would turn the dog loose. It took the dog’s wife and a passer by to pull the dog off my child. Thank God our little girl was wearing a heavy coat! When my husband paid them a visit, they suggested if we didn’t like their dog we could move.
My father seriously suggested poison steak at midnight. It never came to that because a drug deal they were in went bad and the other people killed the dog in retaliation. Poor dog beaten to death with chains and pipes. I felt sorry for the animal, short sad life with stupid owners.