A barn I used to take lessons at had an old thoroughbred mare. I think she was about 23 or so when this pic was taken, anyway, I was just wondering what the darker spots on her could have been cause by. She had them for the last couple of years of her life, and they always varied in shape and area. Would this have been caused by her health declining or something else. She had stomach ulcers for a while, so could it have been caused by that, or something else? She died a few years ago (RIP Avenue), so this is plainly out of my ow curiousity. I've been wondering what caused this for years.