Ambling gait
An ambling gait or amble is any of several four-beat intermediate horse gaits, all of which are faster than a walk but usually slower than a canter and always slower than a gallop. Horses that amble are sometimes referred to as "gaited," particularly in the United States. Ambling gaits are smoother for a rider than either the two-beat Trot or pace and most can be sustained for relatively long periods of time, making them particularly desirable for trail riding and other tasks where a rider must spend long periods of time in the saddle. Historically, horses able to amble were highly desired for riding long distances on poor roads. Once roads improved and carriage travel became popular, their use declined in Europe but continued in popularity in the Americas, particularly in areas where plantation agriculture was practiced and the inspection of fields and crops necessitated long daily rides.
The ability to perform an ambling gait is usually an inherited trait. In 2012, a DNA study found that horses from several gaited and harness racing breeds carried a mutation on the gene DMRT3, which controls the spinal neurological circuits related to limb movement and motion. In 2014, that mutation was found to originate in a single ancestor to all gaited horses. Some gaited breeds naturally perform these gaits from birth, others need to be trained to do them. Some breeds have individuals who can both amble and perform a trot or pace. In the Standardbred breed, the DMRT3 gene was also found in trotting horses, suggesting that it inhibits the ability to transition into a canter or gallop.