In the current world of shoeing fads and gimmicks, it has become quite easy for younger farriers to move away from traditional practices. Unfortunately, monetary gain has made quantity more important than quality. As a result, I find that many lameness cases that I am involved in have been created or, at the very least, made worse by an unskilled or careless farrier.
As a case in point, one farrier in my area has built a great practice using Dr. Ric Redden’s “banana shoe” on numerous competitive horses. He identifies this shoe as a cure-all for whatever ails the horse — something the shoe’s developer never intended or advocated. The only good that comes from the practice is that I’ve been making a lot of money fixing his mistakes.
I have never been in this profession merely for the money. There is no feeling greater than knowing you have made an owner happy or a horse comfortable. That being said, don’t forget that we are in business, so be sure to charge accordingly when doing any corrective work.
Anatomy Knowledge Needed
I assume that most of us have gone to farrier school or through an apprenticeship (or both) and that virtually everyone has read — at some point — an anatomy book.
However, how many of us truly understand what is going on in the distal limb?
Many of us are aware of the bones, tendons and ligaments, but how many of you know at least a handful of farriers who can’t tell you where the deep digital flexor tendon attaches to the pedal bone? Better yet, how many can tell you what that attachment at the semi-lunar crest has to do with articulation of the joint? When we shoe, we tend to be stuck in the mindset of static balance, not realizing what our shoes do when the horse is in motion.
This is my attempt to simplify and explain remedial shoeing options of benefit to a great number of horses. First let’s define remedial, which comes from the same root word as remedy, or to fix. It indicates that shoeing practices labeled remedial are designed to attempt to repair a pre-existing condition.
Recently, I had the chance to watch a well-respected farrier in my area shoe a horse that was previously diagnosed by a well-known veterinarian as having bilateral suspensory desmitis. What is the best way to shoe this horse? The farrier put on egg bars and 3-degree wedge pads. I was floored by this choice of shoes and pads. What would you have done?
I had the honor and privilege to attend the farrier course at Cornell University in Ithaca, N.Y. I was also lucky enough to have Mike Wildenstein as my instructor.
However, I must say that my education in equine anatomy was just beginning when I graduated. Since then, I have become an avid student of the work of Dr. Jean-Marie Denoix. Anyone who has not heard of Denoix should find out who he is. His book, The Equine Distal Limb, is perhaps the finest book ever written on the bones, ligaments, tendons, etc., of the distal limb.
Now, let’s add another new word to our vocabulary: Orthology — the science and study of orthotics. So what is an orthotic?
Orthotic: A device used to support bones, tendons, ligaments or muscles. Using this definition, any horseshoer, regardless of whether called a blacksmith, farrier, horseshoer, marechal-ferrant, hufschmied, etc., is an equine orthotist.
Denoix speaks often of modifying ground-reaction forces. Just what are they? According to Sir Isaac Newton, for every action, there is an equal and opposite reaction.
Consider the following. A horse’s hoof impacting the ground transfers a force of X down into the ground. In turn, the ground then imparts an equal force of X back upward into the hoof capsule.
On soft ground, a certain portion of the hoof or shoe will penetrate into the ground. As orthotists, we can vary the amount of ground penetration through shoeing so that the ground-reaction forces are altered in various parts of the hoof. What this amounts to is what Walt Koepisch Jr. of Dutchtown Forge, Belle Meade, N.J., refers to as “flotation.” A wider-webbed shoe will not as readily sink into soft ground as one with a normal or narrower web. Rather, the wider-webbed shoe floats on the surface.
Think about hikers using snowshoes. They easily walk over the top of soft snow, because they are distributing their weight (and as such the amount of force they have reacting with the ground), over a broader area. The same hiker, wearing only boots, would sink into the soft snow.
A narrow-webbed shoe penetrates the ground more easily. The wider the web of a shoe, the greater the ground-reaction forces. The narrower the web of the shoe, the less the amount of ground-reaction force. More shoe equals more reaction with the ground. Bar shoes, of any kind, add flotation in their design.
Whenever a hoof impacts the ground, the force remains constant. For example, if a hoof impacts the ground with a downward force of 300N, the ground imparts an equal 300N upward into the hoof. By modifying the web of the shoe, we can alter which structures within the hoof share different portions of that ground-reaction force.
Increasing the width of the web of the lateral branch of the shoe to 1 1/4-inch increases the amount of ground-reaction forces laterally, while keeping a 3/4-inch width of web medially would decrease correspondingly the ground reaction forces medially. In the example above, the 300N force would be altered so that 200N would act laterally, while 100N would act medially. The sum would be equal to the total amount of force that the hoof imparted to the ground.
Ground-reaction force and concussion are not interchangeable terms, per se. However, the greater the amount of ground-reaction forces, the greater the amount of concussive forces into that relative portion of the hoof.
We often speak of symmetry. Ideally, all horses should have symmetrical, straight limbs and hooves, with a frog that bisects the hoof capsule, which is in the center of the limb. However in the real world. this seldom happens. But worry not, there are quite a few things that we can do about this situation.
Treating Angular Deformities
Ideal conformation: We’ve heard it repeatedly. “A line dropped from straight through the carpus should bisect the cannon bone, long pastern bone, fetlock joint, short pastern bone, pastern joint, coffin joint and coffin bone (Figure 1).”
The proper method of shoeing the horse with ideal conformation (although I’ve never met such a horse is as follows. At least 50 percent of the mass of the shoe is caudal of Duckett’s Dot, there is an equal proportion of shoe on either side of the centerline of the hoof, which in an ideal situation would be the centerline of frog (Figure 2).
This makes for very easy and very pretty hooves that have no flares or distortions.
A valgus deformity refers to a joint that is displaced medially so that the limb distal of joint deviates to the lateral aspect. The deviation is named for the joint in which the displacement occurs. For example, a horse that is knock-kneed is more properly carpal valgus (Figure 3).
A varus deformity refers to a joint that is displaced laterally so that the limb distal of the joint is deviated to the medial aspect. A bow-legged horse, for example is carpal varus (Figure 4).
In a carpal valgus deformity, the joints of the limb are compressed laterally, while ligaments and tendons that occur medially are strained. In a carpal varus deformity, the opposite occurs.
Think about the side (medial or lateral) that is compressed. For this example, we will focus on a valgus deformity of the right front limb. It would be desirable to increase concussive forces medially, while decreasing them laterally. Why? By increasing concussive forces medially, we are forcing that aspect of the joint capsule back to a more normal state. By decreasing concussive forces laterally, we are allowing that aspect of the joint to open back to a more normal state. Standing at static balance on hard ground, the limb will show little, if any, correction. However, when in dynamic balance, when the support and correction is most needed, it’ll be there. Trim for static balance; shoe for dynamic balance.
What Shoe Types Deliver
By using a shoe with a medial branch 1 1/4-inch wide and a lateral branch that is 3/4-inch wide, we have created a condition in which the medial aspect floats over the ground, while the lateral aspect penetrates into the ground. This in turn creates a situation in which the stresses of the deviation are alleviated when the horse is moving over soft ground (Figures 5 through 7).
When using a medial support shoe, little to no extension is given beyond the normal expansion area in the heels of the shoe. If a medial support/extension shoe is desired, it is suggested that acrylic repair material be used to smooth the transition and prevent stepping off of the shoe.
However, when using a lateral support shoe, extension is easily provided with little fear of the shoe being pulled and without the use of acrylics. As with any extension, make the owner aware of an increased risk to other horses from kicking if the shoe is installed on the hind end (Figure 8 through 10).
Regardless of what form of this shoe is used, another option is to place a leather pad on the shoe. After nailing on this shoe, Play-Doh can be placed over the open portion of the hoof, and a synthetic packing material applied via the hole in the pad. After curing, the Play-Doh is removed. This adds more ground-reaction forces to the opposing side.
Dr. Denoix’s works shows that for bony lesions (ringbone, sidebone, bone cysts), decreasing ground-reaction forces is extremely beneficial, while increasing ground-force reaction is beneficial for treating soft tissues lesions (tendonitis, desmitis, etc.)
Why is that? Quite simply, allowing the shoe to penetrate soft ground decreases concussive forces into the hoof capsule, while causing flotation over soft ground increases concussive forces into the hoof capsule.
When dealing with bony lesions, such as sidebone, shoe modification can be achieved by the use of a belt sander or grinder and flap disc. Noting that sidebone is an ossification, or hardening of the collateral (ungular) cartilages of the distal phalanx, modification to the shoe should begin in the caudal third of the shoe and end at the heel.
In this case, we want to allow the caudal portion of the shoe to penetrate into the soft ground and thereby alleviate concussive forces to that area of the hoof capsule. Using your preferred method, the shoe should be beveled from the inside of the crease (at the last nail hole), to outside of the shoe on the ground surface only (Figures 11 and 12). In this way, a standard wide-webbed shoe can be fit to the hoof and modified afterward without altering the shape of the shoe.
Keep in mind that we are not decreasing the support of the shoe on the solar surface, only the ground surface. The shoe can be fit quite full to the heels, but the smaller area that contacts the ground will help prevent concussive forces from exacerbating the condition (Figure 13).
Building A Simple Lateral/Medial Support Shoe
Grand Circuit is planning on making medial/lateral support shoes available in the near future, but here’s how to build one from a keg shoe.
1. Begin with a keg shoe, which has been properly fitted to the hoof. (I normally use a Delta wide keg shoe, which is 5/16-inch thick.)
2. Cut an appropriate length of round bar — in this case, 5/16 inches. Using a cross-pein hammer and the step of your anvil, radius the round bar to match either the inner or outer radius of the horseshoe; the inner for side support only, the outer for side support plus extension.
Figure 14 shows both a medial and lateral support shoe, ready to weld. I’ve curved the round bar to match that curvature of the shoe using the step of my anvil and my cross pein.
3. Using a wire feed welder (mine is a Lincoln 135 amp, set at wire speed 3 and power D using 0.35 flux-cored wire and no shielding gas) or oxy/acetylene torch, tack the round bar to the shoe at the toe and heel.
I use a welding clamp to hold the bar onto the shoe, while providing for a good contact point. I also tack the heel and quarters so that I can do any final shaping necessary prior to welding.
4. Assure a snug fit by going to the anvil horn and tapping closed any gaps. When doing this, make certain that you do not break your tack weld. Use the same type of face-to-face blow that you’d use to forge out frog eyes. You are bending the bar to meet the shoe, not vice-versa.
5. Now, securely weld both sides of the shoe. The beauty to using round stock that has a diameter the same as the thickness of the shoe, is that you already have a chamfer (Figure 15) provided by the bar with allows for a good, solid weld. When welding, remember to work the weld puddle, taking time to linger on both the shoe and the rod.
You will not have to worry about blow through with this thickness of base material. Don’t forget, the horse has to walk, trot, canter and gallop on these shoes. A weld failure can cause huge problems.
6. Clean up rough edges and box/safe the shoe. I normally use a hot rasp, but a grinder will make the job much faster. At this time, it is also desirable to blend the ends of the welded round bar into the shoe for a smooth transition. This can also be performed on the inner web of the shoe with a 4-inch flap disc or a half-round mill file.
Check to make certain that you haven’t created any sole pressure. Grind the welds on the solar surface smooth and at the same time seat out the shoe. I normally do not clean up the ground surface with a grinder as it will wear on its own.
Back To The Horse
So, getting back to that horse with bilateral suspensory desmitis that we talked about earlier. How would I have shod that horse? Since we are dealing with the suspensory apparatus, which attaches at the fetlock, the use of an egg bar shoe is contraindicated, as it allows floatation of the heels over soft ground, which in turn increases the angle of the hoof capsule.
The additional use of a wedge pad further raises the heel, drops the fetlock down and increases stresses and strains on the suspensories. Raising the heels is totally contraindicated in this case, although it would be an appropriate and effective shoeing modality for a recent injury to the deep digital flexor tendon. Applying what we now know about floatation and ground-reaction forces — and seeing that this horse will be on stall rest — my shoeing choice would be as follows.
An open-heeled shoe which has a wider web in the toe than in the heel (try to picture a toe-weighted shoe), with the same 3-degree wedge pad, but reversed, thereby wedging the toe up and forcing the heel down. With this treatment, the horseshoe would penetrate the soft ground in the caudal-most portion, reducing ground-reaction forces, while the pad would increase stress to the deep digital flexor and alleviate strain on the suspensories until they had time to heal.
Remember, this horse isn’t going to be doing much of anything for a while, so I can get a little aggressive — providing the owner will follow directions and is not foolish.
Working a horse with this form of shoeing is like the guy who fills my propane tanks with a lit cigarette in his mouth. It’s an accident waiting to happen.
Anytime you increase the width of the web of a portion of the shoe, you are increasing ground-reaction forces. Anytime you decrease the width of the web of a shoe, you are decreasing ground-reaction forces.
Right Shoes For The Job
A shoe with a medial branch that is wider than the lateral (Figure 16) is indicated for a carpal valgus deformity as well as for any soft tissue damage which has occurred medially. It is contraindicated for bony lesions occurring medially.
A shoe with a lateral branch that is wider than the medial (Figure 17) is indicated for a carpal varus deformity as well as for any soft tissue damage which has occurred laterally. It is contraindicated for bony lesions occurring laterally.
A shoe in which the web of the toe is wider than those of the heels (Figure 18) is indicated for recent injuries of the suspensory apparatus of the fetlock and its check ligament, as well as for the superficial digital flexor tendon. It is contraindicated for injuries of the deep digital flexor tendon.
A shoe in which the webs of the heels are wider than those of the toe (Figure 19) is indicated for injuries of the deep digital flexor tendon. It is contraindicated in injuries to the suspensory apparatus of the fetlock, its check ligament and for the superficial digital flexor tendon. In this instance, the shoe can also be made into an egg bar or straight bar, both of which essentially increase the amount of surface area into the caudal most region, thereby increasing ground reaction forces. Think back to that snowshoe analogy.
The frog support shoe (heart bar) is a great example of a shoe that increases ground-reaction forces to the caudal aspect of the limb to a maximum — especially when used with impression material. A narrow-webbed, rim shoe would be its diametric opposite, decreasing a maximum amount of ground reaction forces to the hoof, both caudally and dorsally.
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Nicholas B. Denson is a graduate of the farrier program at Cornell University in Ithaca, N.Y. The Wareham, Mass., shoer is a member of the American Farrier’s Association, the Southeastern New England Farrier’s Association and the International Association of Equine Professionals. He is the owner of Denson’s Farriers Service serving eastern Massachusetts and New Hampshire. He also manages a hoof-care Web site, www.EquineHoofcare.com and can be contacted at firstname.lastname@example.org.