Hoof Mechanics Makeovers
Farrier Hans Wiza uses three different case studies to demonstrate how even just one geometry-based shoeing can make a huge difference in a
By: Hans Wiza |
Veteran farrier, Hans Wiza, demonstrates how significant changes can be made in just one shoeing, by using a method that follows the principles of geometry. He shares three different cases, each with a different challenge, which he is able to correct through proper management.
CASE 1: PARIS’ MISMATCHED FEET
A Fantasy in Motion (aka Paris), a pleasure mount, is a 14-yearold 15hh, Quarter Horse mare. She has a big round beautiful body, a long smooth shoulder, nice short back and a long, strong hip, but both front legs grow out of the same hole in her chest, as the saying goes.
Her grazing posture caused her left front hoof to twist extraordinarily and it became the hoof that was always placed back and turned out in her crookedly loaded stance. It collapsed along the medial wall and that caused an upward displacement of the medial bulb of the heel. Even at a walk, her left front foot winged and paddled and corkscrewed itself in and out of the ground.
She was reluctant, unable even, to depart on the left lead, and even with much urging could not hold the lead for more than about three or four strides.
The root cause for lead change issues can be varied and range from ineffective aids to mechanical problems. It is important to understand that as far as a horse is concerned, when left to her own devices, she is on the correct lead! It’s the one that she chose, to make herself feel comfortable and safe. It’s humans who feel compelled to dictate the lead that we want to see.
A problem with lead changes can arise when the front feet are mismatched, as in Paris’ case. A flat foot paired with an upright foot almost invariably will cause a horse to prefer the flatter of the two feet to be the lead leg. The more upright foot will be the one preferred as the primary weight bearing foot. Horses with this conformation will land with the flat foot leading over fences and although they may change a stride after landing, they will always prefer to land the non-upright hoof. What we have here are two different pendulum lengths and two different amplitudes (the limb’s reach, both ways). Flat foot = longer, lower pendulum = longer, lower amplitude. Upright foot = shorter, higher pendulum = shorter, higher amplitude (including a quicker knee-fold). This causes an arrhythmic stride, which can be misconstrued as lameness. The trick is to harmonize their swing and to sync up the crucial points of support in order to create the stability that all horses crave and need.
Try this exercise to help you walk in your horse’s shoes: canter along in your sock feet and change leads. Easy, right? Now, put on a shoe with a heel on it. It is mechanically more difficult to lead with the foot with the heel. Now, jump something – a broom, a stick, a bale of hay, or the dog. Notice how hard it is to convince yourself that the foot with the heel will be as stable as the non-lead leg? Your horse feels the same way.
Canter departs on the correct lead and the ability to hold the lead are all part and parcel of the same problem. Simply cutting down the heels on the upright foot won’t fix the problem, and raising the heel on the flatter foot won’t fix it either – not long-term. There is some merit to shimming with pads, but that is often a temporary fix.
The key lies in bringing the pastern alignments to a point where the fetlock joint is over top of the hoof on both feet. Also, we must try to get the coronary bands at right angles to their respective pasterns.
Looking at a pair of mismatched feet, we see that the flatter angled hoof naturally points ahead and sticks out a little farther than the upright hoof.
The basis of this makeover consisted of finding a common reference point in the trimming of two incredibly different feet. I started by using her heel lengths as the initial benchmark. Both heels on each hoof were trimmed to the same length using the bulbs of the heel as a starting point and trimming the hoof wall so that the heels were parallel to a line across the widest point of the frog and parallel to the bulbs of the heels. The centres of the hoof were determined using my protocol, which strives to manipulate the hoof to create a mechanically efficient posture in all gaits and is based on biometric reference points that have been identified as specific strain points and subsequent fail points in the geometry of the horse’s hoof.
Paris was able to pick up the left lead after the first shoeing and by the second shoeing, she flew around with a trot and canter that would have gotten her pinned in the show ring.
CASE 2: RED BARON’S FLAT FEET
Red Baron is a nine-year-old Thoroughbred gelding. Retired from racing, his new career is lower level dressage as well as the occasional fox hunt. He stands about 16hh and has a modest stature. His feet are the quintessential “pie pan” – flat with a dish at the toe.
As his feet grow, they distort as the result of a long-term geometric imbalance. His toes get way long and out in front of him, and he often catches a toe and stumbles as well as having increasing difficulty picking up the correct lead. Overall, he becomes increasingly heavy on the forehand and reluctant to move forward.
Red Baron lives outside 24/7 from May until November – therein lies one of the biggest challenges to restoring and maintaining a healthy and viable hoof geometry. It is not enough to simply dress the flares from his feet and set a shoe well back on the foot, because the sandy soil he lives on is abrasive. The very fine sand that he loosens up as he walks through the grass scrubs and scours the soles of his feet as well as his horseshoes and horseshoe nails. This very fine yet persistent “sanding” slowly grinds the heels down over time. The toe remains intact, however, so he ends up with shorter heels in relation to the quarters. The quarters then become more prominent in their proportion to the rest of the hoof wall and they pitch the foot on an angle that points the coffin bone sharply at the ground. The pressure on the front of the hoof results in a bending of the wall fibre setting up a “flare.” This flare begins to pull the hoof wall away from a congruent alignment with the laminar bed and the result is a highly stretched white line. One could call this a mechanically induced rotation of the coffin bone.
The sanding also results in wear along the sides of the nail heads as well as along the sides of the crease and even between the hoof and the shoe. The actual nail holes become as much as twice as large as they were when they were new. Very deep wear grooves occur on the hoof surface of the shoe and the result is that the shoe begins to loosen. Not only do the wear grooves loosen the shoe, but due to the nature of the ever present expansion and contraction of the hoof with each stride, the hoof wall begins to wear down ever so slightly as well.
The reduction of the flare at the toe is paramount to the problem. It is very simple to dress back the hoof wall at the toe so that it is congruent with the direction of the coffin bone. This is not a huge issue, until we consider that there must be sufficient wall strength to accept six horseshoe nails safely and without having rasped the hoof wall well past a point that we still have some hard outer crust present.
When the outer wall is rasped too much (only the bottom 40 per cent should be rasped), the problem becomes exacerbated by the fact that there is an un-pigmented layer of horn between the outer wall and the white line/laminar bed. It is a very soft and supple layer of horn. It will accept a horseshoe nail quite readily, but it does not have the ability to withstand the strain of the nails pulling on it, especially when it gets waterlogged from the heavy morning dew and rain. The nails just want to pull through the soft cheesy horn. A harder outer crust tends to keep the nails more rigidly affixed. The subsequent squirming of the shoe under the hoof causes even more wear induced abrasion. This, in turn, leads to more wear and this leads to a geometric imbalance once again.
I like to replace the shoes each time I shoe the horse. Although there appears to be lots of steel present, and there is, the nail holes wear too much and become sloppy. I do not just use a larger nail to reset the shoes because with a fine footed horse, the wall can only accept thinner, finer nails before splitting takes place. Ideally, one should use the finest and softest nail available for the job. This will reduce the instance of fracturing, especially once the overall strength and integrity of the hoof wall has been compromised.
Perhaps the most important part of the process is to be able to set the toe of the horseshoe back so that the inside edge of the shoe is no more than 40mm from the tip of the frog. This reduces the leverage at the toe and decreases the flaring. A short shoeing interval also helps the unwanted trimming (created by the sand) of the hoof to be kept in check.
Special care must be taken to ensure that the quarters do not get too long in proportion of the rest of the hoof. A uniformity of taper from the toe to the heel is mandatory. Ideally, the proportion is a 3:1 toe length to heel length ratio.
A shoeing interval that might be a short as four weeks could be required. The standard shoeing interval is seven weeks and that is based more on economics than the needs of the horse. High maintenance hooves can greatly benefit from a high degree of observation of their state and in turn, flexibility in determining the appropriate time to trim/shoe.
CASE 3: BOB’S FLARED HIND FEET
Bob is a 17.2hh, eight-year-old Hanoverian-cross gelding. He does some light dressage, but is destined for the jumper ring. He is all legs holding up a huge body. His front feet are on fairly straight, but his hind feet had caused him grief. They are dramatically flared to the inside (medially) and the lateral aspects of his hind feet are almost vertical. The hoof, when viewed from the front or back, should resemble a bell. His hooves do not, and that has set up some interesting mechanical problems.
When a hoof has a proper bell shape, the limb comes out of the centre of the hoof head. This allows the horse to move straight. In Bob’s case, the hoof appears to be tipped to one side and it is significantly wider towards the centre of the limb line. When viewed from behind, the ergot is closer to the outside heel rather than centred between the bulbs of the heels as it ought to be.
The inside wall of the hoof is now too close to the other leg. As the swinging hoof moves forward, it swings toward the standing leg and can brush up against it (known as brushing/interference). This can lead to wounds, plus under the skin there can be significant contusion to soft tissue as well as damage to both sesamoid and pastern bones. A good fitting pair of boots can be helpful. It is advisable, however, to be vigilant about fact that while a good pair of brush boots can be beneficial, they also decrease the distance between the fetlocks and can increase the likelihood of interference.
Bob’s hoof, as it touches the ground, is too far to the inside of a vertical line dropped from the point of the buttock. As the leg swings forward, it swings inward and the hoof lands too far toward the inside of the limb line. As the hoof turns outward at the heel, it causes counter rotation of the leg and hoof. This results in “wringing of the hocks,” which, in turn, closes up the joint space along the medial aspect of the metatarsal (hock) bones.
The detriment here is that there is increased compression on the medial aspect of the metatarsal bones, and prolonged irritation to this region results in the development of bone spurs (aka ‘jacks’). This, in turn, leads to reduced hock action and a loss of impulsion.
The hind end of a horse should create a push that is linear, and, ideally, the rider should barely feel the hind feet touch the ground, only the sensation of being pushed forward. When a horse wrings his hocks, there is a feeling of having the hind foot dip or fall away from under the rider’s hip and this can be on one or both sides. When turning in tight circles, the hind end may feel as if it is falling away towards the outside of the circle and the front end cannot fully reach across towards the inside of the circle. This can manifest itself as a lack of suspension and a failure to have or maintain elevation.
Horses with this condition may often find themselves constantly swapping behind without any apparent rhyme or reason, and many of these horses disunite at a canter. Similarly, jumpers may find that they cannot do the tight turns and cannot reach up and around to clear some obstacles especially those where there is a tight inside line.
First of all, the shape of the hoof must be corrected. The flares on the inside of the hoof must be removed, and the symmetry of the whole hoof must to be restored.
Special care must be taken to insure that the ergot is situated vertically between the bulbs of the heels. If need be, a shim may be used along the outside of the hoof, but this must be done judiciously and for the short-term due to other repercussions that can occur with long-term use.
For more amazing hoof makeovers, visit www.hoofmakeover.ca. Hans is also available for clinics, lectures and demonstrations.