A barefoot horse is capable of performing all the tasks that could be expected of a horse, without requiring any kind of protection of the hoof, PROVIDED that the hoof has not been weakened or deformed by the actions of man through unnatural treatment and living conditions. When looking at literature dealing with hooves, the one constant reference is the damaging effect of shoes. For about 200 years, the ill effects of shoeing have been increasingly documented. The textbook written by I.C. Gross, teacher of shoeing at the Royal Veterinary School of Stuttgart, clearly states in the preface that "the question of whether shoeing is the means by which to keep hooves sound, is to answered in the negative."
The fact that two of the main causes of the reduced life expectancy of domestic horses (in Europe, about 1/3 of the natural lifespan) are hoof and leg problems is disturbing and should be cause for research.
Scientific Publications:
That hooves are as hard and resistant to wear as the ground to which they become accustomed is ancient knowledge, already put into writing 2400 years ago by Xenophon, military leader of the Greek cavalry. The argument that "our trails are so rocky, the hooves wear down too much" is thus made invalid, since it is not the hoof, but the living conditions of the horse that cause the problem. Xenophon's observations have been proved many thousands of times over; in more recent times (1986), Alexander and Colles once again reminded the riding and veterinary community of this truth with their article "Shoeing--an unnecessary evil" in the American Equine Veterinary Journal.
Bracy Clark, scientist at the London Veterinary College around 1800, found out that every shoe, no matter how correctly applied, inevitably forces the hoof to contract from year to year. He moreover lamented the fact that the books on equine anatomy portrayed these deformed, contracted hooves as sound hooves, since his veterinary colleagues obviously studied only the (sick) hooves of their patients, not sound hooves. This problem, unfortunately, is still largely present today: there is rarely a hoof shown in veterinary or farrier textbooks which is not a contracted hoof, yet described as a normal, sound foot. DVM Zierold, under Professor Lungwitz in 1910, examined and compared the corium of shod and never shod horses, and found significant differences in structure, in that the corium of a shod horse is of a quality which makes the connection to the hoof capsule less stable (a factor in laminitis, for example).
Luca Bein, in his 1983 dissertation in Zurich, measured the shock absorption of barefoot, shod, and alternately shod horses. He concluded that a conventionally shod horse shows an absence of 60-80% of the hoof's natural shock absorption. He demonstrated that "a shod foot on asphalt at a walk receives THREE TIMES the impact force as an unshod horse on asphalt at the trot." Bein also found that a shoe vibrates at about 800 Hz, damaging living tissue.