Unique coloring on a horse! Read the book "Nobody's Horses: The Dramatic Rescue Of The Wild Herd Of White Sands " by Don Höglund, DVM . Wild horses were described w/similar coloring & determined to be descendents of Midnight. Whose progeny was Peppy San Badger. Isolated & undisturbed for years. Loved the book -wish there had been more photos! (However this is RISE N SHINE DAYDREAM BELIEVR H, WELSH PONY, 2004 (liver chestnut roan with two red roan parents)
This mare has been tested as black and dun genes, so it's spotted grulla. It just doesn't look like a grulla at all! More photos are available: http://www.designsporthorse.com/Ava%20More%20Photos.htm As a foal, it looked like a grulla but I have never earlier seen a horse that changes its color from grulla to... well, seemingly chestnut, only the darker color in hindlegs gives some indication this isn't an ordinary chestnut.