Leash law here and never see dogs in the woods. If you do shoot his dog don't let him know as thingsmightget out of hand.
You might be in the right I really don't know but if someone shot my Brittany for whatever reason I would do something that might land me in jail. It would be like an assault on a close family member.

Thump it with a blunt at 20 yards and it won't be coming back.
I am glad I'm not in your position cause my blood would be boiling too.