Quarter Horse

The Quarter Horse was prevalent in America in the early 17th century. These horses were of mainly Spanish origin until the English horses were brought over. The native horse and the English horse were bred together, resulting in a very compact muscular horse. At this time, they were mainly used for chores such as plowing and cattle work. The Quarter Horse was not recognized as an official breed until the formation of the American Quarter Horse Association in 1940.^[19]
In order to be successful in racing, Quarter Horses needed to be able to propel themselves forward at extremely fast paces. The Quarter Horse has much larger hind limb muscles than the Arabian, which make it much less suitable for endurance racing.^[20] They also have more Type IIb fibers, which allow the Quarter Horse to accelerate rapidly.