Gosh, I really wish I knew a little more about her background.
I realize that's not always possible with a 5yr old dog. My only
experience with adopting a second dog was with introducing a
4 mo old pup to a 2 1/2 yr old resident dog which I think is a lot
easier. At least for me. I do hope someone here has some ideas
for you to try. I wish you the very best with this.