I might let her take a few minutes with some ice water - just a few ice cubes in water, enough to make it very cool - might help with swelling. Trying to think of something that might help.
A very mild comfrey tea might help a little. If it is a break, I am wondering how the jaw could be immobilized but she could still get nourishment. With people, the jaw is immobilized but a bit of wiggle room is left so that the person can use a straw, and all food is pureed.
A creative veterinarian is what I would like to have jump in here right now!