I have some Australorps that are missing patches of feathers (mostly on neck and back) and what feathers they have aren't shinny. However, they have been laying well and don't seem to be sick. I have caught a few of them and sprayed them with lice spray, but didn't seem to help. They free range around 3 hours per day and have plenty of areas to dust themselves. The problem seems to be limited to the Australorps. There is an Orphington, leghorn, and a mixed breed rooster that have a full set of feathers.