I don't like the idea of deadly force, but after what you've been through I couldn't say I'd blame you. It sounds like you need to find a more effective deterrent than the mace you've been using.

The real problem of course is with the owners. If you can get the police involved to talk to them you might have better luck. Common sense doesn't work with some people, but fear of fines sometimes will.

So what happened with the guy on the tractor when you were injured by his dogs. I assume you sued him for all your costs and then some. Yes?