Anatomy of the Horse

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.

The University of British Columbia zoologists John Gosline and Mario Kasapi have investigated what makes horse hooves so tough. They looked at hoof tissue through high-powered microscopes and put strips of it into machines that squeeze and pull, bend and tear, all the while measuring how the tissue responds to the various forces. Along the way, they’ve shown that the material making up a hoof is enormously complex.

When picking out the feet, look for signs of…

  • Thrush. The first clue to this bacterial condition (usually caused by prolonged standing in manure, mud, or other wet, filthy conditions, or even by the use of pads) is a foul smell and dark ooze from the cleft of the frog. Later, the frog becomes cheesy in texture as the fungus eats away at the tissue. Thrush can cause lameness and significant hoof damage, its early stage is simple to treat.
  • Puncture. If a nail or other object pierces your horse’s sole and then falls out, the entry wound will probably be invisible by the time you pick his feet and you’ll be unaware of it until it causes an abscess. In some cases the object remains in place, to be discovered when you brush the last bits of dirt from the sole.
  • Cracks. Some cracks are superficial; others can worsen, involving sensitive hoof structures, without appropriate trimming. (One cause of a crack is a hoof abscess–see below–which breaks out through the coronet band at the top of the hoof, creating a weak spot in the hoof wall that must be attended to as it grows out.) If you notice a crack in your horse’s hoof, call your farrier and describe its location and size so they can decide whether it needs attention now or can wait until the next visit.
  • Abscess. If your horse’s digital pulse feels stronger than usual and/or is foot is warmer than normal to the touch, the cause could be an abscess inside the hoof from a badly placed shoeing nail, a bruise, or an overlooked sole puncture. Your routine check can alert you to the problem and get your veterinarian or farrier involved if nessary.