The horse’s foot is an engineering marvel. No other animal has to bear as much weight, let alone the forces generated during movement at high rates of speed, on a single rigid structure.
Elephants, camels and rhinos have big, flat, sponge-like feet. Gazelles, deer and other herbivores distribute the forces on a hoof with two claws, with an elastic connection between them. Only the horse attempts to get by with a single digit.
It’s not surprising, then, that the horse is prone to hoof problems. We believe you should think long and hard before doing anything to your horse’s foot that interferes with the way that particular hoof was designed to function.
In theory, it seems like common sense that altering the balance of the foot or the angle/heel height will change the pressures on the joints. However, the farriers who practice a lot of corrective work — or are pressured by some trainers to do so — can be pretty slow to admit that there might be problems.
For the disbelievers, a study performed at the University of London and published in the March 2003 Equine Veterinary Journal describes what happens to pressures within the coffin joint when the heel height is altered or the foot is unbalanced from side to side.
A high-heel configuration increases the pressures along the front of the joint, and with lateral imbalance the high side shows increased pressures. The authors conclude that “a balanced foot is the ideal and that the elevated heels may be detrimental to long-term viability of the DIP (coffin) joint.”
Foot problems of all types, including those we often consider to be degenerative conditions related to age or hard work, will almost always have improper hoof mechanics as part of their cause. In some cases, it’s a large part of the cause. If a horse has foot pain and the hoof isn’t properly trimmed and balanced, the first step in alleviating the discomfort should always be to correct the current problems, not create new ones.
For example, let’s take navicular disease or heel-pain syndrome, which can seem to be like navicular due to the heel-area pain but lacks X-ray changes of navicular bone degeneration and inflammation.
By the time a horse with heel pain is lame enough to have an examination and nerve blocks, odds are his feet are going to show narrow/contracted heels, a foot that is obviously longer than it is wide, narrowed-to-atrophied frogs, and probably high heels.
These changes are all related to the horse attempting to minimize bearing weight on the painful heel area. However, there’s a good chance that the problem developed in the first place at least in part because the shock-absorbing capacity of the frog, quarters and digital cushion were not all they should have been.
As the horse began to feel heel pain because of poor cushioning, his response was to unload the heels as much as possible, leading to further atrophy of those very structures the horse needed to protect him.
Many common navicular trimming therapies make sense. Toes are backed up and beveled or squared to ease breakover. When shod, a bar shoe, often fit wide at the heels, is a common choice.
Soft packing material is often used to provide cushion. These techniques basically restore the foot at ground surface to a configuration that more closely matches what the horse should have ideally in the first place.
The foot is now closer to being as wide as it is long, the bar shifts the impact surface to the back of the foot, where it should be, and the soft packing material approximates what would happen normally when an unshod hoof contacts the ground by providing frog pressure.
So far, so good. We have correction only in the best sense — a change toward normal. Other adjustments — such as leaving out the posterior one or two shoe nails and fitting the shoe somewhat full through the quarters and heels — also help encourage the hoof to expand normally.
Where you can get into trouble with navicular therapeutic work is automatically raising the heel without giving the other measures adequate time to work.
The horse may seem to be more comfortable for awhile because elevating the heel takes pressure from the deep flexor tendon off the navicular bone, and vice versa.
However, raising the heels to an abnormally high degree inhibits hoof expansion, decreases natural shock absorption, and encourages further contraction at the heel. The result is a progression to worsening shock absorption, concussion, and heel pain.
All too often the correction that is then used is again to raise the heels more until there’s nowhere left to go and the foot is further weakened and deformed. At that point, the navicular has degenerated to the point you probably can’t reverse the changes.
Toeing In And Toeing Out
Winging/paddling (the foot swings in and outward) and dishing (the foot swings inward) are undesirable in the show ring. The movements can be caused by the cannon bone being somewhat offset to the inside or the outside or, more commonly, a deviation below the fetlock that makes the toe point either in or out. Legs that angle inward tend to cause paddling, while a toed-out horse will usually swing his feet inward when he moves.
Lowering one side of the hoof is often tried to correct the toe in-or-out problem, but it can become more of a problem if it is overdone, especially on a mature horse. The horse can compensate well for bones that aren’t aligned perfectly straight, and even extremely crooked-legged horses may stay sound as long as you don’t interfere with the way they move.
When it comes to corrective shoeing, often less is more. Be sure your farrier understands your horse’s movement, age, what he is going to be used for, activity levels and discipline.
The best therapy or method of correcting a horse’s hoof problem is usually to restore the foot to as close to the ideal configuration and balance as possible — the balance he developed with before he was broken. Corrective work should only be done on growing foals when the hoof changes will affect the bone growth in a positive manner.
Changing an adult horse’s way of going by disrupting his hoof angle and balance will also affect his upper structures. The difference is that the older horse is not capable of compensating for these changes. Deliberately forcing a horse to move more the way you would like him to is usually just a temporary fix, and you’ll pay a price in the horse’s soundness sooner or later.
Corrective or therapeutic trimming/shoeing should be reserved for cases that need changes to alleviate pain. And then, those changes should be made to move the horse toward a more normal hoof balance and structure, not a quick fix to relieve pain but that also sacrifices the natural angle and shock-absorbing capacity of the horse’s hoof.