I had this happen (it wasn't my dog) to my cochin pullet about a month ago. I definitely can't stress enough the need for antibiotics. No matter how clean you can get the wound, it won't be clean enough. And, there may be punctures you can't see right now, which are nasty wounds. Once he's calmed down a bit, try to go over every square inch of him to see if you missed anything. You should flush the wounds with very diluted iodine (the color of weak tea, I was told).
My little lady was doing okay with us cleaning out her wounds every other day, but really, really improved dramatically after a course of Penicillin G antibiotics. I'm pretty sure that without it, she would have eventually died. I just got the Penicillin at my Theisens here in town (farm supply store.) It's in a refrigerator case, and it cost me about $9 for a medium-sized bottle. The syringes were cheap too. I gave her once a day subcutaneous (not really very hard, once you get the hang of it) injections for 5 days. I think her dosage was 3 cc's, but you should look it up.
Within a week or so after we started antibiotics, she was back to her feisty self, and her wounds healed super, super fast! As soon as she got enough feathers back to cover the bald spots reasonably well, we put her back out with the other ladies.
Search on this board for dog attack threads...there are a lot of great ones with pictures and advice. Hang in there, and good luck!
Angela