light horse, any breed of horse that is used primarily for riding or for light work such as pulling buggies. Light horses have their origin in the Middle East and N Africa. All modern breeds of light horse trace their origins to the Arabian horse, usually through the Thoroughbred. Light horses are classified according to training, e.g., racers, trotters, riding horses, and cow horses. See also pony, American saddlebred horse, Appaloosa, Morgan, palomino, Pinto, quarter horse, and Standardbred.