I'm not sure. I think at first it might make him back off and re-evalutate his decision to confront me with such a high level of aggression, but then again he may get used to that. I don't think it would make him turn and run, as brave as he is. I might have to just get creative and see what I can come up with. Even if he doesn't find something scary, perhaps the irritating noise of pots and pans or rattle cans is enough to eventually make him want to leave. I have thought about dog-deterrant sprays, but haven't tried them just yet. My first action after helping Mud was to fill the gap at the bottom of the fence. It wasn't large by any means, but just big enough for his muzzle to slip under and grab Mud's leg. He's a medium-sized dog, maybe 50 pounds if that. Like I said, he hasn't been out lately so fortunately he hasn't caused any problems as of yet. I've even tried some training with him. He's so aggressive that I of course can't get too close, but I have tried avoiding eye contact with him and using my body language to project confidence but not aggression. I try to make myself seem as neutral as possible, and never walk head-on towards him. I usually ignore him completely but keep a wary eye on him at all times. When he shows no aggression, I've tried continuing to ignore him(rewarding him because there is no stressful attack situation and he sees that I don't pose a threat). I thought of tossing food when he shows no aggression, but I don't want him seeing me as a food source or thinking that being near me means he gets rewarded. I'd prefer that he ignored me entirely. Anyway, I've tried using my body language in a variety of ways to see how he reacts and try to teach him without actually getting too close that I am no threat to him or his property. Nothing has worked. When he decides to act aggressively, of course I have to defend myself so that just makes him regress more. He does not in any way seem to be the fear-aggressive type, as I've never even seen him so much as lay his ears back. Lol, I need to get a llama. Llamas and canines are natural born enemies, and a llama can and will attack a dog if it feels threatened. They can easily kill one(not that I'm a cruel-hearted witch and want the dog to die), and will protect their pasture-buddies without hesitation. Donkeys are usually the same way, but unfortunately it's the minis that usually get attacked. They just can't defend themselves against a large dog.