I agree with others suggestions of clipping feathers back from wounds and clean them thoroughly. Saline and iodine will work fine, I've never had to deal with injuries like this but I've taken some notes. The first cleaning should be the most vigorous to make sure you clean out as much bacteria from the wounds as possible being that the dogs mouth is not very clean. You will need to clean the wounds daily, most people will rinse the wounds daily with saline or iodine/water solution using a syringe and paper towels and apply vetericyn spray and an antibiotic ointment each time. In other posts, birds have been less mobile and lower than normal appetite for up to a week and im not sure if that's from pain or conserving energy to recover but I feel like that note in behavior change is worth mentioning cause it seems to happen so often. To help with decreased appetite offer anything your hen likes, some food is better than no food, scrambled or raw eggs, tuna, fruits and veggies, regular feed mixed with water to make a wet mash and of course offer her dry feed and water at all times. Getting her antibiotics to take orally would also be a good idea but I don't know what would be best to give nor the proper dosage so hopefully someone will come along with suggestions there. I wouldn't put too much blame on your dog, I don't believe there was any ill intent on the dogs part but for future reference it's important to contain your birds safely when you aren't home. I had a neighbor with chickens growing up and they always liked to fly over my fence and my dog just wanted to play with them but my dog didn't know how to do that gently, luckily none of the neighbors chickens were ever injured but my point is your dog may have been trying to play and it got out of hand. Good luck with you hen, hope she makes a full recovery.