Shoeing your horse versus allowing the horse to go barefoot is a controversial topic, and I will say up front that there are many different and very strong opinions on this subject. Some folks firmly believe that no horse should ever have shoes, while others believe shoes are ok. Dr. Steve O'Grady from Virginia indicates that the equine foot with healthy structures is superior in its natural or barefoot state as opposed to the shod state with regards to the weight of the horse, shock absorption, and dissipating the energy of impact. Shoes are applied for a number of reasons including protection: when wear on the ground surface exceeds growth at the coronet, increasing traction or as a therapeutic aid in the treatment of lameness. There are some aspects of leaving a horse barefoot that should be considered for a horse competing in less rigorous events, and pleasure horses may do fine without shoes assuming the horses is given time to adjust to being barefoot. D. O'Grady indicates he has had success in improving the hoof capsule in the heel of the hoof in some horses by leaving them barefoot for a period of time.
It is important to realize that a horse shoe is not an extension of the horse's foot as it changes the properties of the hoof-ground interaction. Without a shoe, there is one interface between the ground and the hoof, and with a shoe there are two interfaces: one between the hoof and the shoe, and then between the shoe and the ground. Also, a shoe elevates the hoof off of the ground, resulting in less heel expansion. There are some horses that need to be shod and some that can go barefoot and you cannot make a blanket statement that all horses need shoes or all horses do not need shoes. All horses are different.