Various materials have been used for horseshoes but the two most common are steel and aluminum. Steel shoes are more durable and less expensive but aluminum shoes are used because many folks believe the lighter weight allows better movement for certain disciplines. It has been shown that increasing the load on the legs by having a heavier shoe can increase strain on the legs and therefore increase the risks of lameness. However, there is little actual evidence on the effect of different shoeing materials on gait quality. The more weight on the foot, generally the higher the flight arc of the hoof, the greater flexion of the horse’s lower leg joints and improved quality and animation at the trot. A study was published in the Journal of Equine Veterinary Science in which horses were observed at four different gaits with both steel and aluminum shoes. The weight of the steel shoes were over 2.5 times the weight of the aluminum shoes. The most significant finding of the study was that horses with steel shoes had more knee flexion. Also, maximum hoof height was lower in horses wearing aluminum shoes compared to those in steel shoes. So horses with more weight on the hoof from the steel shoes demonstrated more flexion of the carpus and a higher hoof height than horses with aluminum shoes. Although the aluminum shoes are lighter, there is increased knee action and higher hoof flight with the heavier shoe.
So if you are in a performance discipline in which you want less knee action and lower hoof flight, aluminum shoes may be desirable. For horses competing in judged events where the desired movement is sweeping with little action of the knee, an aluminum shoe may be helpful. However, for performance events, benefits of the aluminum shoe may not be significant. The belief that aluminum shoes result in longer stride length and greater suspension is not supported by this study.