So many things here are unacceptable. I have had mostly large dogs. My avatar, Bozo, was mean AF - part Fila, and took after that part of his ancestry. Very loving and easy to handle for us - hated everyone else. He was usually muzzled when off the property except while in the car; the vets were warned (and were thankful, they get bit a lot by dogs that don't bite); he was not allowed off lead. Period. It's called being responsible.
You come over my fence and get nailed by my dog, that's legally your fault in this state. You will likely go to jail after you get out of the hospital. Off the property - that's my fault. In this state, if you are attacked by a dog when you have the right be where you are unless you have provoked it - that's the owner's butt.
This dog needs to be controlled. The owner's conduct is simply not even close to responsible. With this history (and long before this last attack), every time that dog is off the property is a 911 call. Period. The situation is well past the point of being nice to anyone - be effective. Keep calling. Every neighbor who sees it needs to be calling 911. If there is an attack in progress, I am pretty sure it will not be stopped without a shooting. If you have not dealt with a larger strong dog that is attacking or resisting you, you have no idea what a problem you have. Making lots of 911 calls makes a record of the problem. There is a good chance of litigation. So be it.
Self-defense is pre-emptive. A dog that lunges with serious intent (like the Shepherd on the trail incident) likely needs to be shot, RFN. I am not a fan of doing so, but I am not a target nor a chew toy. Don't want to see your dog get hurt because someone could not read its language and took action? Keep your dog under control. Not a real hard concept.
Bozo's successor Ted is fascinated with other dogs. He wants to meet them, sniff, have a pissing match, etc. He has doggy pals - we go across the street to see one so it does not get in trouble for crossing to see us. Fine. Approach in an attacking mode? I'll make it clear with my voice that the dog needs to be controlled. Offend people with my attitude and language? Yup. Beats the heck out of injuries to any of us. My neighbor has two dogs - a Malamute that will happily interact with Ted and I, and a Dobe that protects the yard with ferocity. She has gotten lose twice - smart little thing. She is actually friendly, away from her turf. She gets a pet, I holler for the neighbor, they come get her.
Ruby does not care for other dogs. She was simply not socialized with them before we rescued her and it is unlikely to change. We avoid the problem areas - it's called being responsible.
