Noticed a smell of ammonia and inspected her hindquarters, discovered her gut was pierced. Decided to euthanize.
Thank you all for kind words, good information, and quick responses. Unfortunately our first thread here does not have a happy ending.
Here are the other pictures I've managed to take of her, it's tough to move her head enough to see the whole thing.
Flap of skin is gone, no longer attached.
Feathers missing on chest but no holes that I can detect.
Her skin seems to be completely torn off at the neck. Her eyes are open and she's looking around, but she's never been so calm. We sprayed some vetarycin plus on the wound because it's what we had on hand and we're keeping her warm.
One of our hens has been attacked by a dog. Most resources say to clean the wound and keep her separate. Wanted advice from the community. Image attached, I think. It's my first post.