What Every Horse Owner Should Know about Shoeing

Originally appeared in Trail Blazer magazine 2009

What Every Horse Owner Should Know about Shoeing Monique Craig www.Epona-Institute.org

The Trim, Load on the Frog, and Hoof Shape The trim is one of the most important aspects of shoeing, no matter what medium is being used (composite shoes or metal shoes.) Some people forgo the shoes altogether, however many horses cannot maintain nice hooves unless they wear some form of prosthetic. Horses never evolved to be ridden, and breeders and riders alike do not always make the wisest choices in selecting function versus form in a horse.

Figure 1: The relationship between Hoof angle and Heel angle affects the foot length. Here, in one month, the hoof has improved.

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

A good trim should help maintain the hoof at its optimal health. The hoof still contains a “pad” even after millions years of evolution. The horse’s limb is designed to load primarily into this pad, which is called the “digital cushion”. The hoof therefore should stand under the bony column, meaning the hoof should not be very far ahead of the pastern and cannon bone. The entire sole should provide enough support area to the pedal bone and limb.

The angular difference between the hoof angle and heel angle should ideally be in the neighborhood of 8 degrees (see the ‘after’ photo in figure 1). The frog should occupy a large portion of the hoof.

The Coronary Band’s Shape Viewed from the side, the coronary band should appear as a slightly curved smooth arc over the quarters. However, the coronary band should not be pushed up or show sign of deformities.

Figure 2: The shape of the coronary band is not straight – but neither should it be ‘pushed up’ or bulging unnaturally. In figure 2A, a wedge pad system has just been removed. Several months later, the rear portion of the hoof and coronary band has been able to relax down to a more natural shape (see areas indicated by the red arrows). The collateral cartilage (1) and the coronary cushion (2) are affected by capsular deformities.

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

The Biomaterial of the Hoof It is important to realize that the hoof’s outer layers are composed of a biomaterial called keratin which has certain mechanical properties. The study of physical properties of materials is called material science. This field generally describes properties of certain materials whether they be man made materials like iron, or a biomaterial like silk or keratin. The study of mechanical properties of materials involves properties such as strength, stiffness, and resiliency.

Figure 3: Man-made materials such as plastics, elastomers, and composites have mechanical properties which are similar to the hoof’s keratin. Aluminum and steel are quite different.

Metal Shoe Use and Disadvantages A hoof that is shod with metal will behave quite differently than one that is left barefoot or wears a boot or a composite shoe. For one thing, metal shoes Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

only allow the hoof to flex at the heels whereas a hoof that is barefoot or wearing materials that are more synergetic with the behavior of the hoof and the keratin will move three dimensions.

Metal shoes were primarily invented for preventing the hoof from overwearing on hard roads. The first true metal shoe with nails appeared in Europe around 1000 AD. There is a tendency for the metal shod hoof to take the shape of the shoe, therefore it is very important that the right type of metal shoe is applied on a horse. A good farrier understands this. There are very different trains of thought within the farrier profession as to what constitutes a good shoeing job. Some farriers are minimalists and tend to only use a plain metal shoe and they will only resort to other specialized shoes when absolutely necessary. Others tend to have a rather impressive arsenal of shoes styles and forms at their disposal. The more metal on the hoof, the more limited the movement of the hoof. Good farriers tend to not overshoe hooves.

As usual in life, things do not define themselves in black and white; there are occasions where hooves need to be immobilized for a period of time.

Eggbar and heartbar shoes accomplish this purpose. If I had no other option than using an eggbar or heartbar shoe I would always use a pad also.

Packing and Support of the Frog These days, farriers have more options for providing frog support than just the traditional eggbar or heartbar shoes. This can be accomplished with pads and packing material. Personally, I don’t like metal to go over the frog. The digital cushion is a rather sensitive area and is not meant to load into metal.

The barefoot horse in nature is often naturally packed with dirt or mud. The use of man-made packing is a sort of artificial “clean� dirt. Man-made packing not only provide the same benefits of a packed hoof (as it seems nature intended) but it also provides added shock absorption to the hoof and gives the farrier more control over the details of the environment under the hoof.

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

Figure 4: A Metal shoe augmented by a pad and packing material to provide some support to the frog. Image courtesy Stephane Tournier.

Hoof Flex and Impact of Frog Support People love to argue about how the hoof flexes or doesn’t flex, how much it should or shouldn’t flex. These discussions are complicated by the fact that the shoeing system itself can play a role in how the hoof flexes. In particular, allowing some of the weight to be borne by the frog (as a barefoot horse, or a shoeing system with frog support) changes fundamentally the way the hoof flexes under load. The cartoon in figure 5 is an oversimplification, but it helps to keep this situation in mind.

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

Figure 5: A hoof which is supported by a rim shoe on its wall only, and particularly if that shoe is flat and smooth, will expand outwards at the heel under load, as shown in the upper cartoon. A hoof with some of the load shared on the frog, and especially when not on a slippery surface, will not display this spreading of the heels, rather, a slight wall bulge.

Both upper and lower cartoons are exaggerated to make this point.

To Clip or Not to Clip, and Trailers Side clips are used to stabilize shoes from twisting off the hoof. These are generally used on horses that do strenuous athletic work – like going over fences on turf. Toe clips are to be avoided as far as I am concerned. There is tremendous stress at the toe area as the hoof pushes off during locomotion.

This is definitely not an area that should have increased stress placed upon it. There are ways to reduce some of the stress at the toe. Some farriers will

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

bevel the shoe and therefore remove more material in the front of the shoe.

Some farriers bevel the shoe and the roll the toe.

Figure 6: I’m not a fan of toe-clips.

Trailers are used to reduce the twisting motion of a hoof. It is an artificial way to reduce or stop exaggerated twisting which most often occurs in the hind limbs. I feel that it is rather dangerous to make assumptions about the mechanics of a particular horse. We don’t have enough data on what is a ‘normal’ range of motion for a particular horse. Biomechanics is rather complicated and I feel that starting to tamper with locomotion for some perceived ideals is rather unwise and dangerous. Note that farriers do not always have a choice on whether they should or should not put trailers on shoes. It is quite common practice that a trainer or horse owner will demand trailers on their horses’ shoes to reduce perceived locomotion problems.

Nails and Nailing on Shoes Nails are a very old, tried and true, means of attaching a shoe to a hoof.

They cause some minor hoof wall damage, but whether this is a problem or not depends very much on the quality of the hoof wall of the particular horse. Striving to avoid nails has led to the development of some glue-on Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

shoes and other methods of attachment, such as boot systems. My thinking on this has shifted over the years – I wanted to avoid nails when I started years ago. But in the end, nails are a good means of attachment, and I don’t think they are the real source of any trouble. If I list the problems I face as a farrier, they are things like laminitis, ring bone, thin soles, heel pain, poor trimming, remodeled bones, etc; none of these problems can be blamed on nails. With metal shoes, nails become one more aspect of the rigid constraining of the hoof which I want to avoid; but nails in a flexible composite shoe can move as the shoe-hoof combination flexes, so they are again less of an issue.

Figure 7: The basic steps of nailing are shown here: (1,2) show driving the nail, which bends outwards due to taper design of the nail. In (3) the nails is clipped off (or can be ‘twisted off’), in (4,5) the block is used to set the nail, in (7,8) clenchers fold over the tip of the nail, and the finished nailing is shown in (8).

Part of the skill of the farrier is to nail so that the nail emerges at the proper height on the hoof wall. Poor nailing can result in a nail that is called a “low nail” or a “high nail”. Low nails risk cracking the hoof wall and not securely attaching the shoe. High nails are better for good attachment, but if too high they risk disturbing sensitive internal structures.

Toe Bevel, Shoe Bevel, Shoe Wear, and Toe Growth There is a lot of discussion and many theories concerning the shape of the toe and/or the shape of the shoe at the toe. Some believe in beveling the shoe, some do not; some believe in beveling the shoe but not the toe, others Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

do not. Once again, the answer may be “it depends”. But generally, I believe in not invading hoof wall to set a bevel, but rather, the bevel should be placed in the shoe. The placement of the shoe (how far back) also enters into these discussions.

Figure 8: The left image is on the day of shoeing, and the right image is 6 weeks later. I beveled the hoof at the toe, and over the natural growth cycle of the hoof, the toe grew down to meet the shoe. The composite shoe beveled itself in accordance with the horse’s motion (some wear at the shoe is a good thing.)

Figure 9: A metal shoe with a built-in “roll” at the toe can be a dangerous thing. It takes extreme skill by the farrier to trim the front hoof wall properly to match up with such a shoe. It is very difficult to anticipate the exact amount of hoof growth during a six weeks shoeing interval. Look again at figure 8 to see how the hoof wall at the toe naturally grows out during the shoeing interval.

Copyright 2009 by The Epona Institute

Originally appeared in Trail Blazer magazine 2009

I tend to like metal shoes that are slightly beveled at the toe, but not pushed up into the front hoof wall. Bevels are good because simply by adding a layer of material to the hoof, one lengthens the lever arm out to the toe.

Rolling the shoe and setting the shoe slightly back will help reduce this lever arm at the toe. Again, the amount of toe bevel and the distance to set back the shoe depends on the situation. Metal shoes should not be set back so far that at mid stance (when the limb is fully loading into the sole) the tip of the pedal bone ends up loading into the metal shoe. With composite shoes, one has more options because the sole is often directly loaded into a softer material.

Give the Hoof a Rest There was a time when farriers would advise their clients to remove the metal shoes from their horses and give the hooves and their horses some rest. I used to do it when I was a little girl in Switzerland. We usually did not ride our horses year-round and if we did so we removed their metal shoes. Metal shoes are not evil if used and managed correctly. Metal shoes have helped many horses from over-wearing their hooves. In today’s world, there are many more options for reducing wear at the hoof -- from boots to composite shoes. The choice of shoeing medium is much broader than it used to be.

Copyright 2009 by The Epona Institute