Thanks everyone for their thoughts. It looks like on-leash greetings must stop--not that I care about that anyway. Giving up the dog park is going to be really hard, but I'm keeping this in mind as a distinct possibility, if not probability.
I'm going to start carrying around high-value treats and really get "leave it" and "watch" firm. Maybe take an e-collar class to try to solve the chase/nip behavior.
I’d be careful using an e-collar for corrections while nipping/chasing another dog. He can learn to associate the quick shock with dogs, and get even more dog aggressive.
I do use an e-collar on Lyka, because she still has some leash reactivity, but never use the shock or stim buttons. She’s great with just the noise button. As soon as she hears that noise, her attention redirects back to me.
We keep the Husky on a prong for walks, it’s the only thing we can find that he won’t pull through. We tried the e-collar, on all settings, and had to keep amping up the level because he would have zero reaction to any of it. My GSD will startle at the shock level set to one. We went all the way up to 28 with no results. Finally, we went to to 50, and he looked back at us, then just kept on pulling, even if we hit the button again. He never reacted after that first reaction. And we ordered the extra long prongs for the e-collar and trimmed the bajesus out of his coat where the e-collar prongs touched, still nada.
We don’t do dog parks period, it’s just a disaster waiting to happen, especially if they aren’t separated for small dogs/big dogs. And not because mine will charge and attack other dogs, but because my dogs have no interest in the other dogs, and the other dogs get all up in their face when mine are trying to stay away from them. With enough pestering, my GSD will soft bite, but of course the owner of the other dog just sees a GSD’s mouth on their dog, and get all hysterical and blame us, even though it was their dogs persistent annoying behavior that prompted it.
If you want to continue with the dog park, I suggest you get some pretty heavy insurance that will protect the actual dog, and not just an add on for your homeowners insurance. One bite is all it takes for someone to sue you for everything you have. And