Trimming and shoeing, done right and at the right time, help keep a horse sound and performing at his best. But what’s “right,” and how can you know if your farrier is shoeing your horse correctly?
Every horse is different, so what’s best for one horse may not be so good for another. Still, the principles that guide the farrier are the same regardless of the horse’s individual conformation or the work he does. In this article I’ll explain the core principles and how they’re applied in basic trimming and shoeing. I’ll also tell you how to recognize and deal with some common problems related to this work.
Balance and Breakover
The guiding concept in trimming and shoeing should always be biomechanical efficiency.
Biomechanical efficiency simply means that, at any gait, the horse completes each stride with as little effort as possible. He wastes no energy, so he tires less easily. Efficient movement helps the horse be a better athlete.
The way a horse’s hooves are trimmed and shod influences the way they land and push off from the ground, and that affects biomechanical efficiency. For the horse to work at his optimum level, his hooves must be balanced. That means they land flat (or slightly heel first) with the outside and inside portions of the hoof wall meeting the ground at the same time. They leave the ground heel first and roll over with minimal resistance.
The location of the breakover point—the last point of the foot (or shoe) to come off the ground—is a key factor. Breakover is most efficient when it occurs at or near the toe, and the right length of toe is important. Long toes delay breakover and act like levers on the foot, putting stress on the wall and on interior bones, tendons and ligaments. The farrier can influence both balance and breakover with 1) the trim and 2) the type of shoe and where it’s placed on the hoof.
Ideas about proper hoof balance have changed over the years and so have concepts about how to achieve it.
Hoof angles are a time-honored standard. Traditionally, a horse would be trimmed so that the angle of the dorsal (front) hoof wall, relative to the ground, was 50 to 55 degrees in the front hooves and 55 to 57 degrees in the hind hooves. Few farriers follow this standard as closely today as in the past. The reason is that the hoof angle should ideally mirror the angle of the coffin bone inside the hoof. That can vary from horse to horse by up to 10 degrees, and without an X-ray it’s practically impossible to know what it is.
Pastern alignment is another traditional standard. The farrier trims the hoof so the angle of the pastern matches the angle of the dorsal hoof wall. While this concept is still widely used worldwide, there are some downsides. The main one is the risk of removing too much wall or sole in the effort to make the angles match. The external hoof capsule is designed to limit concussion and protect the coffin bone and the soft tissues of the foot, and trimming away too much causes the horse discomfort. A horse needs strong hooves with good integrity to perform.
Center of balance is the key to a widely used system that was devised by farrier and educator David Duckett in the 1980s. Instead of focusing on the hoof wall, the farrier identifies a point on the sole that corresponds to the central balance point of the foot, which is directly below the center of the coffin joint. This is simply done by locating the widest part of the sole. An imaginary line drawn across the sole there will pass through the central balance point.
The farrier then measures to make sure that in the trimmed hoof, the distance from the line to the toe is the same as the distance from the line to the heels. When there are equal amounts of hoof in front of and behind the line, the heels have the support they need and the toe is at the right length so it won’t act like a lever on the internal structures. One of the great advantages of Duckett’s system is that it provides a simple yardstick for determining the correct breakover point in any horse. Before this system was introduced, adjusting breakover was guesswork.
The farrier also trims the hoof wall for correct medial–lateral (side-to-side) balance, so that weight is distributed evenly across the coffin bone and other structures in the foot. Unless the horse has perfect conformation (which is rare), this doesn’t mean that both sides of the hoof wall should be the same height. Many horses toe in a bit, for example, and that causes their hooves to meet the ground at an angle. If the walls are trimmed to the same height, they’ll land unevenly—first the outside wall, then the inside—putting unnatural stress on the foot.
Instead, the hoof should be trimmed to ensure that the two sides meet the ground at the same time, even if this means the outside wall is a bit shorter than the inside wall. In fact, this is how the feet would wear naturally if the horse went unshod. For a horse to truly work efficiently, the hooves have to be trimmed in relation to his conformation.
Shoes affect the health and efficient functioning of the foot, and they’re an important part of the farrier’s role in addressing hoof-capsule problems.
Fit. Shoes should give support to the entire wall, heel to heel, and should always be shaped to fit the horse’s trimmed feet—feet should not be trimmed to fit shoes. Ideally, the toe of the shoe will sit directly below the wall at the front of the hoof. From there the shoe will get slightly wider than the wall as it follows the contour of the hoof toward the heel, allowing space for the hoof to grow and for the heels to expand. A horse with low heels or weak hoof walls may benefit from more width in his shoes to give more support.
Placement and design. Shoes can be designed and placed to improve biomechanical efficiency. It’s not always possible to trim a hoof to the ideal breakover point, for example. There may be limits to the amount of hoof that can be removed, or deformation of the hoof capsule may make it difficult to identify landmarks like the widest part of the sole. By using shoes with rolled or rocker toes or by setting the shoe back under the front of the hoof capsule, the farrier can move the breakover point back and reduce stress on the foot.
Nails. Nails should be placed only where hoof wall permits and in the front half of the hoof capsule, no farther back than the widest point of the hoof. In a nicely finished shoeing job, nails are clinched smoothly at the wall and line up parallel with the ground. Such details don’t really affect function, but they’re a sign of quality workmanship.
After the Farrier Leaves
When your horse has brand-new shoes, you don’t expect to call your farrier until it’s time for another new set. But keep that number in case these problems pop up:
Soreness: I like to think that if a horse is sound before he is shod, he should be sound after, too. If your horse is sore after shoeing, contact your farrier immediately to identify the underlying issue. Pack the foot with an anti-inflammatory product until the farrier can get to the horse. The cause can be as simple as a hot nail—a nail placed a bit too close to the sensitive tissue in the foot. The farrier can pull the nail. A horse may also be sore if the farrier had to do a lot of corrective trimming.
Keeping the foot packed for a few days will generally reduce inflammation. But if the horse is routinely sore after shoeing or if soreness lasts longer than a couple of days, have your vet look at him. Whatever the problem is, the vet and the farrier should work together to solve it.
Lost shoes. Horses lose shoes for numerous reasons. Correctly applied shoes won’t just fall off, but any horse can take a bad step and pull a shoe that way. Sometimes conformation plays a part; a horse with a short back and a long step is more likely to overstep and take off front shoes, for instance. The farrier can help by easing breakover in the front feet to help them get out of the way faster. Owners can help by using bell boots.
Controlled turnout will also help prevent lost shoes. If your horse grazes with others, be sure that the group settles well together so there’s minimal racing around. Paddocks with dry footing will increase your chances of keeping the shoes on, too. And be sure that your horse is trimmed and reshod frequently enough that his shoes don’t become loose. Loose shoes can be dangerous even if they don’t come off—a loose nail can damage the hoof wall or push into the sensitive tissues.
I always recommend that owners and trainers pack the hoof as soon as possible after the horse loses a shoe. Doing this will help stop the walls from breaking up and allow the farrier to put the shoe back on with little to no damage to the foot.
Small problems with hoof balance can be hard to spot as the horse moves, but over time imbalance produces distortions in the hoof capsule. You can see these changes if you stand your horse square and view the feet from all angles, then pick up each foot and examine from beneath. Look for:
• A flare or dish at the toe or on either side. The distorted area is under stress.
• Vertical cracks at the toe or at the quarters, wherever imbalance puts excess pressure on the wall.
• Compacted growth rings. Growth rings, the fine horizontal lines that run across the hoof wall, should be evenly spaced and parallel to the coronary band. When one part of the foot bears more weight than the rest, growth is slower and the rings will be closer together. (Prominent growth rings sometimes appear after illness or changes in diet or exercise.)
• Sheared heels, a sign of medial–lateral imbalance. Both heels should be the same height. If one heel takes more weight than the other, it will be pushed up over time, a condition called sheared heels.
• Underrun (collapsed) heels, which develop from long-toe, low-heel imbalance. Over time the heels gradually become so low that they’re crushed forward, becoming part of the weight-bearing surface.
• Contracted heels, which develop when the horse puts more weight than normal on his toes. Over time the foot takes on a boxy shape, the frog narrows and the heels grow tall and narrow.
• A distorted sole or frog. The ideal sole is basically symmetrical with similar amounts of hoof on each side of a plump, healthy-looking frog. Excessive width to one side of the frog or a narrow frog with a deep fissure at the base can signal imbalance. Thrush can also appear.
Conformation is often the root of these problems. For example, suppose the horse toes in. If the hooves aren’t trimmed to accommodate that conformation, they won’t be balanced. Flares and other hoof-capsule distortions will develop, and joints, tendons and ligaments will be under unnatural stress. That can lead to unsoundness.
Unsoundness can also cause hoof-capsule distortions. The horse weights or places his foot differently to ease discomfort, and the hoof capsule responds by changing shape. Narrow, boxy feet and clubfeet (with tall heels and a nearly vertical wall at the toe) often have underlying issues, for example. Work with your veterinarian and the farrier to identify the cause. X-rays should be taken before any work is done.
A horse’s front feet (or hind feet) often don’t match. One front hoof may be a bit flatter than the other or have a slightly different shape. Conformation or a soundness problem, rather than poor shoeing, may be a reason. A farrier may be able to force hooves to match or trim them to make a horse seem to stand or move straighter, but artificially changing the foot can be the quickest way to lameness.
You’re In Charge
As the horse’s owner, rider or trainer–or maybe all three—you know the horse best because you see him every day. You’re also the person ultimately responsible for his well-being. It’s up to you to keep him on a regular trimming and shoeing schedule.
Many adult horses need the farrier every five to eight weeks, but the interval between shoeings varies enormously. Keep an eye on your horse’s hoof growth, and set up a schedule that gets the farrier to your barn before the shoes get loose or the feet outgrow them. You can help ensure that the horse is shod to the best of your farrier’s ability by providing safe working conditions and adequate lighting and by making sure the horse is settled before the farrier arrives.
Communication is the key to a successful relationship with your farrier. The more information you give him, the better he or she can adjust your horse’s shoeing to suit his needs. Describe any lameness issues, changes in the horse’s attitude to training or other concerns before the farrier starts working so adjustments can be made. If you have questions about the way the horse is shod, ask. A good farrier won’t resent questions and should be able to give straightforward answers.
Outside and Inside the Hoof
Your horse’s hooves are brilliantly engineered to bear weight and provide shock absorption.
On the outside:
• The hoof capsule forms a shield protecting the critical structures of the foot. It’s made of horn, tough tissue packed with keratin, a protein, and has no nerves or blood vessels.
• The hoof wall grows down from the coronary band at an average rate of a quarter inch a month. It’s thickest at the toe and gradually thins toward the quarters (sides) and heels. At the heels the wall turns in to form the bars, two ridges on the sole.
• The sole and frog are covered by thinner layers of horn. The frog is the most flexible part, with a consistency similar to hard rubber.
On the inside:
• The coffin joint is the core of the foot. Three bones meet here—the coffin bone, the small pastern bone above it and the navicular bone tucked at the back. Interlocking structures called laminae secure the hoof wall to the coffin bone.
• The deep digital flexor tendon, which helps support and flex the leg, runs behind the coffin joint and attaches to the bottom of the coffin bone. Between the DDFT and the navicular bone is a fluid-filled sac, the navicular bursa.
• The digital cushion, a pad of fibrous tissue, sits under the heels and the frog. It’s nestled between two broad wings of cartilage that run back from the coffin bone.
When the horse’s weight comes down on his foot, all these structures work together. The DDFT helps support the joint while the navicular bursa protects the bone from pressure. The digital cushion flattens, pushing the cartilage wings out (and, at the same time, helping circulation by forcing blood up from the foot into veins in the leg). And because the hoof wall is thinner at the heels, it also expands a bit. Then, as weight comes off the foot, everything springs back into place.
Stuart Muir, NZCEF, CJF, APF, joined the podiatry team at Rood and Riddle Equine Hospital in Lexington, Kentucky, in 2012. Before then, he practiced full time in his native New Zealand, shoeing some of the country’s top eventers and racehorses.
This article originally appeared in the December 2015 issue of Practical Horseman.