Swayback is a condition in some horses that causes a horse's back to sink down between the withers and the hip of the horse. This can be a genetic condition or can be caused by the breakdown of support tissue due to improper riding during the horses life. Swayback is a condition that occurs in older horses typically. Some breeds are more prone to becoming sway back, such as Saddlebred horses. In Saddlebred horses, the swayback condition is genetic. This condition is called Lordosis.
If you have a swayback horse you should be especially concerned about saddle fit. To make sure your saddle fits your swayback horse you should have a professional saddle fitter check your saddle. The saddle fitter may suggest a special saddle pad for your swayback horse, extra saddle pads, or a cutback saddle and saddle pad to allow for the pronounced withers of a swayback horse.