My very large Australorp rooster has what looks like an abrasive injury on his chest. He has not been fighting, so the only cause I can think of is his roosting 2x2. This morning it looked very raw and was larger than it was yesterday. He has an area about 3" square without feathers, and a raw area about 1" square within the bare surface. How should I treat this? Usually I don't worry about such things, but he is one of my favorite roosters.