I have a 14 year old black & white tobiano Spotted Saddle Horse. He is primarily black; he has white legs, two white spots on his neck with a mixed mane & tail.
Just in the past 6 months, he has formed a new white patch of hair on his neck (about baseball-sized). He also has started to develop some roaning on his neck and rump.
I thought that only very young horses undergo color changes. How common is it for middle-aged horses to have some color change?