In the 4th Century BC there were writings advocating natural hoofcare and the importance of diet, exercise, and living conditions in the health of the hoof. Xenophon, a Greek author, philosopher, and cavalry commander wrote in his books "On the Art of Horsemanship" and "On the Cavalry Commander":
The same care which is given to the horse's food and exercise, to make his body grow strong, should also be devoted to keeping his feet in condition. Even naturally sound hoofs get spoiled in stalls with moist, smooth floors. The floors should be sloping, to avoid moisture, and, to prevent smoothness, stones should be sunk close to one another, each about the size of the hoofs. The mere standing on such floors strengthens the feet. Further, of course, the groom should lead the horse out somewhere to rub him down, and should loose him from the manger after breakfast, so that he may go to dinner the more readily. This place outside of the stall would be best suited to the purpose of strengthening the horse's feet if you threw down loosely four or five carloads of round stones, each big enough to fill your hand and about a pound and a half in weight, surrounding the whole with an iron border to keep them from getting scattered. Standing on these would be as good for him as travelling a stony road for some part of every day; and whether he is being rubbed down or is teased by horseflies, he has to use his hoofs exactly as he does in walking. Stones strewn about in this way strengthen the frogs too."
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