Thanks for the advice, folks! I’ll try to spend a little more time reading blogs, watching videos, and doing actual training exercises at home. I already knew we’re definitely not ready for her to be loose around horses yet, was just wondering what more I could do to enforce safe behaviors around them while leashed \ tied.
Preposterous Ponies - Thank you for saying it’s fear not aggression. One of my neighbors suggested she MAY have been on the loose since last spring. If so, that’s a pretty long time to earn a healthy mistrust of people and other dogs. This is all still new to me. In our very early days together, she was horrible with EVERY stranger. She would do OK if I picked her up to introduce a person, but if a stranger approached with her on the ground, she was awful. I didn’t want that to be a 100% of the time crutch, so I’ve been working with her every time delivery guys or friends come over. I’ve been asking her to turn her attention back to me, and sit, or lie, or other things to earn treats, rather than bark at the stranger, and using commands like “good visitor” (weird, but it was the best I could come up with) and “good quiet” when she shuts up. I’d say we’re having improved success with quite a ways to go. But with other dogs, I’d say it’s pure aggression. She sounds positively worflike horrible to them, and when she gets close enough, she dominates by jumping on the back and nipping ears.
Saultgirl & Countrywood - thanks for the three years and one year comments … I have to remember that we’re not in a race. I’ve only had her three months, and most of that has been working on getting her healthy! I have been taking her with me to the barn and leaving her tied where she could watch what was going on. I may still do that, because the mile RT trek is good exercise - she’s a high energy dog! But I don’t have to be in a hurry to turn her loose.
Beowulf - It’s funny how therapeutic it can be to even write out a silly question on a forum like this … I have a tendency to write a lot, and as I was entering my tenth paragraph, I pared it all back to as simple as I could. I realized as I wrote that if I don’t have “leave it” and “come” as rock-solid always-works commands, then she doesn’t belong around horses yet. So your first sentence is spot-on. I will add “out” to her vocabulary.
For “Come” I’ve been working on that with her on a 20 foot zip line as we walk to the barn. I load myself up with training treats and will mostly let her zip out wherever she wants to go, but randomly call her back with “come.” If she comes, she gets a treat. That’s been working pretty well, but when she gets set on something like a squirrel or other critter in the bush, she doesn’t listen. So I think these are good opportunities to keep it up and the day she does listen when excited she’s going to get the whole freakin’ treat bag. 
(And no one asked, but just for the record, I did everything I could to find an owner when I first found her … craigslist, facebook, helpinglostpets.com, registered with animal control in three counties, flyers at all the vet offices, flyer up on my own mailbox that everyone in the neighborhood has to drive by because I’m at the start of a few miles of roadways that all dead-end. This girl clearly had training about not going potty inside the house, but that was the only indication she’s been with people.)
