
It is the job of the hoof to hit the ground hard enough to generate a force that can propel the horse forward. We hope for a fluid, pain free motion at all gaits. On the surface, a hoof seems like the worst thing to move a 2000 pound animal. A horses’ leg ends in what is literally a giant toe. This animal descend from an ancestor that had five digits, which evolution has stripped down to only one - for a reason. The hoof is a giant toenail that has evolved into a thick wall wrapping around the foot. It is made of keratin, the same kind of protein found in human nails and can crack like it too. A horse hoof is a complex working landing zone and on a microscopic level is very amazing.
Horse hooves are among the most crack-resistant substances when balanced, about twenty times tougher than bone. The life of a horse demands this sort of toughness. As the animal runs hard and fast over rough ground, it needs to avoid damaging its hooves, which, like fingernails, are dead tissue that cannot heal themselves. Cracks, hoof wall separation and bad spots need to grow out. Any crack that reaches into the living tissue inside the hoof would become a prime site for potentially life-threatening infections.