Standardbred

Horse

Standardbreds are a breed of horse best known for their ability to race in harness at a trot or pace instead of under saddle at a gallop. Developed in North America, the breed is now recognized worldwide for its harness racing ability. They are solid, well-built horses with good dispositions that are also used under saddle for a variety of equestrian activities, particularly in the Midwest and eastern United States.

http://en.wikipedia.org/wiki/Standardbred_horse