I had a long drive today transporting two dogs and it gave me lots of time to think. I don't know alot about Rat Terriers - but from what folks are saying they are really hardwired to hunt and exterminate so I was thinking on ways to reduce her anxiety by giving her legall outlets for her instincts plus a mental workout. There a number of games you can introduce her to that might help with that. Many dogs like to "search and destroy" - it plays to their instincts.
Taking her meal (if it's kibble) and hiding it in stashes around the room for her to find and consume. Start out easy, with her watching from her crate so she see's where you put it, and then letting her out to find it. You can up the difficulty - adding some height, place it in a small paper bag or twist or toilet paper tube so she has to work at getting it out and the scent is less obvious. You would need to babygate her in so she's the only dog doing it.
If her first action upon getting outside is to hunt - maybe set up a game for that to - so yes, she can hunt, but it's with your rules. Hide food in an easy to find area, put her on a long line, and let her find it. Make it obvious at first, then gradually harder. When she finds it - she gets to consume it, but even better - you drop one at a time several more treats on the spot to encourage to her stay there and get rewarded instead of hustling off. You can increase difficulty of hides as she gets better - even using toilet paper tubes, burying it in a shallow hole, hanging it from something. I'm thinking it gives her an outlet to work off some of her anxiety, give her a job that's in line with her instincts plus - improve your partnership. It might indirectly help with the potty issues as well.
I do some of this with my guys with nosework, but haven't tried it with meals and I think I might.
Another thing she might enjoy is putting kibble in a Buster Cube - she has to work at getting it out and that will tire her out.
