Chicken attacked by dog...healing but missing feathers

Hi All!

I have a flock of 6 Rhode island reds that are 5 months old. 2 weeks ago one of them was attacked by a dog & was bitten on her back down to the muscle. She has healed beautifully with a combination of cutting out all of the feathers around the wound, sprinkling the wound lightly with sugar & a 10 day course of antibiotics. The only thing that hasn't happened is none of the feathers have regrow not or even begun to regrow. We reintroduced her to the flock yesterday & 2 of the others are constantly pecking her whenever they see her. Ironically our 2 khaki cambells are acting like her protectors & chase off the other 2 & have been by her side at all times. For the time being we are keeping her in a dog kennel in the coop at night for her own protection. I've read that as long as those feathers are missing they will continue to go after her. How long should it take to regrow the feathers & should we cover the area with something so that it's not obvious to the others that she is different. Prior to the injury she was definitely at the top of the pecking order...she's clearly not now! Any advice would be appreciated as we are new to this! Thank you!!