Getting fluids in her is most important. If you have electrolites, then give her some of that. Fluids should be room temperature to slightly warm until she's not so shocky. Make sure she's in a warm, quiet place. You can warm towels in a dryer and put around her to help her warm up. Sick birds can become hypothermic. If she won't drink then you may need to learn to tube fluids, this is a good link for that:
https://www.backyardchickens.com/threads/go-team-tube-feeding-updated-12-29-2019.805728/
She is probably very sore also, and that may take a while. Flush all the wounds well with chlorhexidine (hibiclens), sterile saline, or plain, mild soapy water. Veterycin spray is also good to use. Once dry, apply plain neosporin or plain triple antibiotic ointment to cover all wounds and keep them moist. Keep her crated on clean bath towels or puppy pads, change as needed to help keep her clean. Monitor droppings. Offering some feed moistened with warm water, scrambled or cooked chopped up eggs, canned tuna, see if she will be tempted by those, once you are sure she's hydrated. If there are no internal injuries, and no infection sets in she has a chance to recover, though it will take some time. I would consider having an antibiotic on hand since this is dog bites and extensive. You can get amoxicillin as a fish antibiotic on line as aqua mox without a prescription. Dose would be 57 mg per pound of body weight every 12 hours for 5-7 days. I would also examine her for any wounds hidden in feathers, or any bone fractures, when she's perked up a little bit. Bruising may show up and will often look greenish. This thread has some pictures of some wounds during healing, which may be helpful in knowing what you will be seeing:
https://www.backyardchickens.com/threads/wounds-pictures-of-how-they-heal.1325817/#post-21627607