Luna is a 6 yo, indoor (also screened patio,) medium haired, Russian Blue mix. She is in very good health, not having ever experienced any issues. Over the years, on an occasional random basis, she gets these apparently denuded spots appearing on her head and ears (but not her body.) As far as I can tell, I have never seen her scratch herself in any manner that would cause these spots...the skin shows no signs of trauma, nor does she have bugs. She pays no attention to the spots when they occur, and they always go away without any ensuing problems. Any idea what is going on? There is a pic of the spots. Thanks.