American Quarter Horse: There are two main body types: the foundation type (commonly referred to as bulldog type) and the appendix type. The foundation type is shorter, more compact, stocky and well muscled, yet agile. The appendix type Quarter Horses are somewhat taller and smoother muscled than the stock type, more closely resembling the Thoroughbred.
Step 2. There’s a horizontal line above the topline; a vertical line going down to the ground from above the croup down the outside of the back leg; and a vertical line going down in front of the withers. Keep in mind the horse’s proportions. Measure the head from the poll to muzzle. You can find that rough length in different parts of the horse: from withers to croup, from elbow to coronet, etc.From The American Quarter Horse Journal. Illustrations by Rushe Hudson