Colorado Sundown
1952
KoKo, "The Miracle Horse of the Movies", was a white-maned, white-tailed chocolate-coloured chestnut stallion trained by Hollywood's premier equestrian specialist Glenn H. Randall Sr. (as was the legendary Palomino Trigger ridden by Roy Rogers). It was purchased from Randall at the age of ten by cowboy actor Rex Allen. imdb.com