"Microphthalmia with multiple ocular abnormalities in 11 horses: a novel syndrome" noted a novel ocular syndrome in horses characterized by bilateral microphthalmia and aphakia associated with multiple ocular abnormalities, and given the predominance of anterior segment lesions, a defect during the embryological development of the lens placode was suspected. The breed exhibits a natural ambling gait, called the single-foot, which replaces the trot seen in a majority of horse breeds. Both gaits are an intermediate speed between a walk and a canter or gallop; ambling gaits are four-beat gaits, whereas the trot is a two-beat gait. The extra footfalls provide additional smoothness to a rider because the horse always has at least one foot on the ground. This minimizes movement of the horse's topline and removes the bounce of a two-beat gait, caused by a moment of suspension followed by the jolt of two feet hitting the ground as the horse shifts from one pair of legs to the other. The value of an intermediate speed is that the horse conserves energy. More than thirty horse breeds are "gaited," able to perform a four-beat ambling gait, and some can also trot. Thus, a Rocky Mountain Horse, with rider, can use the single-foot to cover rough ground at around and short stretches of smooth ground at up to . The faster speed is known as the rack. In comparison, the average medium trot speed is . History Eastern Kentucky is known for its gaited breeds, created through a mixture of Spanish horses from the southern United States and English horses from the North. American Saddlebreds, Tennessee Walking Horses and Missouri Fox Trotters also originated in the same general geographic area, from the same mixing of Spanish and English blood. Rocky Mountain Horses have a similar history to the Kentucky Mountain Saddle Horse, and together are sometimes called "Mountain Pleasure Horses". The Rocky Mountain Horse originated in eastern Kentucky from a foundation stallion brought to the Appalachian Mountains from the Rocky Mountains around 1890. Brought to the area as a colt, oral histories state that the "Rocky Mountain Horse", as he was known, possessed the preferred chocolate color and flaxen mane and tail found in the breed today, as well as the single-foot gait. He was used to breed local saddle mares, and due to the small area in which he was bred, a local strain of horse originated. This foundation stallion