The most ordinary observer will soon find that the outer portion or covering of the mule's foot possesses very little animal life, and has no sensibility, like the hair or covering of the body. Indeed, the foot of the horse and mule is a dense block of horn, and must therefore be influenced and governed by certain chemical laws, which control the elements that come in contact with it. Hence it was that the feet of these animals was made to bear on the hard ground, and to be wet naturally every time the horse drank. Drought and heat will contract and make hard and brittle the substance of which the feet is composed; while on the other hand cooling and moisture will expand it, and render it pliable and soft. Nature has provided everything necessary to preserve and protect this foot, while the animal is in a natural state; but when brought into domestic use, it requires the good sense of man, whose servant he is, to artificially employ those means which nature has provided, to keep it perfectly healthy.
When, then, the foot is in a healthy state, wet it at least twice a day; and do not be content with merely throwing cold water on the outside, for the foot takes in very little if any moisture through the wall. In short, it absorbs moisture most through the frog and sole, particularly in the region where the sole joins the wall. This, if covered by a tight shoe, closes the medium, and prevents the proper supply. Horses that are shod should be allowed to stand in moist places as much as possible. Use clay or loam floors, especially if the horse has to stand much of his time. Stone or brick is the next best, as the foot of the animal will absorb moisture from either of these. Dry pine planks are the very worst, because they attract moisture from the horse's foot. Where animals have to stand idle much of the time, keep their feet well stuffed with cow manure at night. That is the best and cheapest preservative of the feet that you can use.