In my experience, over time not much scarring is left from just one brawl. What color is your dog? Dark dogs show scars more. They always look worse the first couple weeks after and accident, but when the fur starts growing back you won't see them as much. One of my dogs has been involved in a few accidents over the course of his life (the trouble maker is 8 now) and unless I am really looking for them, I can hardly see them except for a few particular scars.