With the back measured from peak of withers to peak of croup, exceeds 1/3 of horse’s overall body length. Usually associated with long, weak loins.
Especially seen in gaited horses, Saddlebreds, Thoroughbreds, and some Warmbloods.
The horse's ability to engage back depends on its ability to elevate the back and loins, requiring strong back and abdominal muscles. A long back is flexible, but harder for horse to stiffen and straighten spine to develop speed or coil loins to collect and engage the hindquarters to thrust rear limbs forward. This then affects upper level dressage, cutting, reining, barrel racing, and polo: sports that require rapid engagement of the hindquarters. Reduced flexion forces the horse to jump flatter with less bascule.
It is difficult to develop a long back's muscle strength, so a horse is more likely to fatigue under the rider and to sway over time. The abdominal have more difficulty in compensating, so they are also less likely to develop. Loins and hindquarters may swing more than normal, increasing the occurrence of sore muscles which leads to a stiff, rigid ride. Cross-firing or speedy cutting likely at high-speeds from a horse with a long back.
Movement of the back is flatter and quieter, making a more comfortable ride and is easier for horse to change leads. Short back
The horse's back measures less than 1/3 of overall length of horse from peak of withers to peak of croup
Can be seen in any breed, especially in American Quarter Horses, Arabians, and some Warmbloods
The back may lack flexibility and become stiff and rigid. If vertebral spines of back are excessively small, the horse may have difficulty bending and later develop spinal arthritis. This adversely affects dressage and jumping performance. If still in back and torso, the stride will become stiff and inelastic. The horse may overreach, forge, or scalp itself if the hind legs do not move straight.
The horse may be handy and agile, able to change direction with ease. Good for polo, roping, cutting, reining. If the horse has good muscling, it is able to support weight of rider with rare occurrence of back pain.
Conformation bst used in agility sports