Chicken attacked and severly wouned...Need Advice

We have a beautiful hen that was attacked last night and has been injured quite extensively. I believe the animal that did this to her through the wire fencing was a raccoon, possum, or possibly a cat of some kind. We live in the country in WA and have just found out that two of our other hens have been killed/taken a day ago, which I can only assume is from this same animal. We have 11 chickens in a large coop/run area and had 3 free roam. after we saw that the 2 had been possibly killed (feathers everywhere in two separate locations) we rounded up the last free ranging one and placed her in her own coop/pen to keep her safe. This clearly did not happen and I was awoke at 1:30am to her freaking out. I let my dogs loose and saw that the animal they had sniffed out went up a tree (so not a fox or coyote).
Now my main issue aside from trying to catch the killer is that her right side has had some extensive damage and huge areas of feathers and skin are gone. Her wing bones are exposed as well as her right side "meat" areas as well as her back of her neck. She is moving around. she came out from the coop and ate some berries I picked for her. Any help would be appreciated. I am saddened to have lost two of our girls already and would hate to lose another.

I'm so sorry for your loss and hope your girl makes it. I have a chick that was really hurt and had a wing ripped off by rats. I was advised to keep it inside nice and warm. To clean the wounds with peroxide one time and place some neosporin on it. There after to clean the wounds with watered down betadine twice daily and apply neosporin. He's doing really well so
Far.
We're on day three.

Welcome to BYC. That looks like too serious an injury to take care of by yourself with bones exposed. She needs vet care if that is possible. I would use weaken betadine or chlorhexadrene (hibiclens) to clean the wounds. Put plain antibiotic ointment such as Neosporin on it twice a day. If her wing is not salvagable, it may need to be removed. I'm so sorry about the injuries and deaths, but you need to use 1/2 inch hardware cloth fencing all around your coop and run to prevent the hands of raccoons and others from this.

I've healed a wound that was like that. Although I do worry about the wing. Ours was attacked by a dog. The chicken had a broken wing, a broken leg and a wound in her body cavity that you could see all the way to her spine. I pulled the feathers out of the wound and cleaned it as best I could with sterile saline spray. Then I got some silver nitrate like this

http://www.cvs.com/shop/health-medi...al-silver-non-staining-clear-gel-skuid-445926

Clean and reapply daily, either the silver of a wound gel. Cover wound lightly with a dry dressing just to make sure she doesn't kick up to many shavings into the wound. The key is to keep the wound as clean as possible and nice and moist on the inside. If she is eating that's a good sign.

Our bird couldn't walk. I suspended her from a towel in a large rubbermaid container. I rotated her as able offered her free water and food hanging from the edge of the container, then lots of treats. She loved berries, meal worms. I made her all kinds of mash and stuff anything to get calories in her. At first she was suspended most of the day with little breaks to lay in the sun and the grass. Then as the leg healed which was weeks, we eventually moved her to a small cage and back to the coop.

I was amazed that she lived. She was outside untreated overnight. I found her the next morning with snails in her wound, but when I brought her inside she immediately started to drink, so I decided I would put the effort into helping her.

She walks with a slight limp, but she is healthy and happy.

Thank you all for your help, sadly she passed away the day after my post. She had much more damage than I initially thought. We believe the predator was a raccoon from paw prints on the roof that I found so as soon as my husband gets home from CA we will be beefing up security and unfortunately wont have any more of our chickens roaming free, but just sticking to their large attached pen. I appreciate all the advice given.

So sorry for your loss. Many people free range during the daylight hours without a problem, but they should always be locked into a coop at night. Of course that doesn't mean that there will never be a daytime predator attack, but for me I like to let them out to roam.