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Karen Tappenden
Bottom of hoof before the trim
Too much toe for a good balance
The primary role of any professional farrier, trimmer, or hoofcare provider, is to provide proper trimming of the horse’s feet, in order to keep the horse as comfortable and healthy as possible. For the vast majority of horses, optimum care is best achieved when the horse is kept on a routine trimming schedule. For most horses, this should not exceed eight weeks of hoof wall growth. Some horses, to the untrained eye, may appear to have little growth, but in fact have grown well beyond the parameters that offer optimum health and comfort. Each horse has their own unique conformation, hoof quality, speed of hoof wall growth, as well as varying levels of physical demands placed upon them. Many horses benefit greatly just by decreasing the time elapsed between trimming appointments. By keeping a horse correctly trimmed on a regular, consistent basis, the hooves can function most effectively.
When a horse’s lower limbs are supported by correctly trimmed hooves, there is a direct benefit to the soft tissue and bone structures of the lower limb, and consequently the whole horse. For the hoofcare provider, it is of tremendous benefit to have a good working knowledge of the art and science of modern farriery. When a horse has a lower limb with subtle deviations in conformation, which is quite common, a keen, experienced eye can be invaluable to the horse’s wellbeing. Proper trimming involves the ability to evaluate a horse’s needs and make changes accordingly. It doesn’t matter whether the horse is barefoot or shod, the same fundamental principles apply.
Properly trimming the hoof is most often referred to as “balancing” the hoof. A horse is most comfortable and moves most efficiently when each of its hooves is said to be properly balanced. So what does it mean to have a properly balanced hoof? A hoof or foot is considered to be balanced when the anatomy of the foot that is in contact with the ground is at the correct measurements to best support the soft tissue and bony structures that lie above it. This occurs when the weight of the limb is equally distributed over the weight-bearing surface of a properly trimmed hoof. In order to provide this for the horse, the educated practitioner fortunately has external reference points that can be relied upon to inform their work.
This article will cover two important external reference points that aid the hoofcare practitioner’s ability to evaluate a horse’s needs. Some knowledge of these reference points can be very valuable to horseowners and trainers in better understanding the work of their farrier. One important external reference point is the horse’s frog, which accurately pinpoints the location of the coffin bone within the hoof capsule, and therefore informs the farrier on where the parameters of the outside hoof wall should be located in a healthy foot. A second external reference point is the shared angles of the hoof-pastern axis and shoulder axis, which provides significant information in assessing the natural and optimum angle for the hoof.
In most cases, the structure of the horse’s frog makes it possible to know exactly where the coffin bone is located without the use of a radiograph, basically giving the trimmer a way to look inside the hoof capsule. In every horse, with some obvious variation between drafts and miniatures, the center of the coffin bone can be located 3/8 of an inch behind the apex or point of the frog, referred to as “the dot”, or Duckett’s Dot, explained and made famous by British farrier David Duckett. The frog also makes it possible to know where “the bridge” or “Duckett’s Bridge” of the foot is located, by measuring approximately ¾ of an inch from the point of the frog. The bridge is the center of the foot on the ground surface, from which point there should be an equal amount of hoof forward to the toe, and backward to the heels. The bridge also marks the widest part of the hoof. By knowing this, we are able to consistently know where to place the breakover, verify proper heel placement, and recognize distortion of the hoof capsule as a whole. The breakover point is that part of the hoof found at the toe, which is the last part of the foot to leave the ground when the limb is in flight. If a hoof is too long in the toe, there is a physiological imbalance creating excessive strain, which often may cause distortion of the foot as well as damage to the bones, tendons, ligaments, and soft tissue. When breakover is in the right place, the biomechanics of the horse can optimally function. Having the location of the bridge also dictates where the heels should be weight bearing, which coincides with the widest part or base of the frog. If weight bearing is forward of this point, then unhealthy concussive and compression forces will damage the heel region. By using the frog as an external reference point, it enables the hoofcare provider to know the correct parameters for trimming any given horse.
The hoof-pastern-shoulder axis refers to the shared angle of these three anatomical areas. Horses are designed so that they will have bones below the fetlock joint that are parallel with one another when a horse is standing with their weight on the limb. These bones are the long pastern, the short pastern, and the coffin bone. The coffin bone and the bottom portion of the short pastern are found inside the hoof capsule. Viewing a horse from the side, or profile view, an imaginary line drawn through the center of the hoof and pastern will be approximated by a parallel line drawn thru the center of the shoulder angle. When there is a deviation from this angle that the hoof and pastern share with the shoulder, the biomechanics of the lower limb becomes less than ideal. Generally it is normal to have horses with hind limbs that have a hoof-pastern axis that is a few degrees steeper than the shoulder angle with no ill effect. When assessing your horse, draw an imaginary line from the horses withers to the point of the shoulder. Compare that angle to the angle of an imaginary line through the middle of the pastern and hoof wall while the horse is standing square with weight on the limb. If the angle of the hoof wall doesn’t share the same axis as the pastern and shoulder, this may indicate that healthier hooves can be achieved through changing the horse’s hoof angle.
In addition to the two external reference points of the frog and the hoof-pastern-shoulder axis, it is helpful to know that the pastern bones attach to each other by way of hinge joints, meaning they are designed to move forward and backward, with very little sideways movement. In order to support this anatomy and not cause strain to the joints and corresponding connective tissue, it is important that the hoof be trimmed so that the inside and outside of the hoof wall are symmetrical in length from toe to heel. Since the anatomy of the lower limb is designed to only move forward and backward, if for example, one heel is higher on the inside of the hoof than it is on the outside, this creates imbalance and strain on proper function. A healthy hoof requires medio-lateral (inside and outside) balance of the hoof wall to best support the internal structures. When standing in front or behind a horse that is standing on a flat surface, this is viewed as the ground surface of the hoof being perpendicular to the bone column.
Through routine care and the use of external reference points to inform their work, hoofcare providers have a greater ability to achieve and maintain the best care for a happy, comfortable horse.
Michael Waldorf has been a lifelong equestrian and a full-time professional farrier in Eugene, Oregon since 1997. Michael is a Certified Farrier with the American Farrier’s Association and an Accredited Professional Farrier with the American Association of Professional Farriers. He can be reached at www.happyfeethoofcare.com or mikethefarrier@gmail.com