First I would just thank God she is alive. Most chickens don't live through a dog raid/attach. I'd give her a little recovery time, maybe a week or so, then assuming she is still alive and well, you could pull any broken feathers you find. If there are a lot, I'd suggest doing this in stages if the damage is extensive, it takes a lot of calories and energy to regrow feathers and you don't want to stress her anymore than she already has been. Good luck.
Oh you might want to check your fences/runs or wherever she was housed to see if there is damage done to your fencing.
