This article was printed in the American Farriers Journal May / June edition 2011. As I read through it and gave it some thought: I do not think there is much that I would change 9 years later. Have a read…
Think Before You Wedge Those Heels
Without proper supporting structures, you may cause further damage to the palmar aspect of the foot you are trying to help
By Pat Tearney, Managing Editor
Before making the decision to raise the heels of a horse, farriers should ask themselves two questions:
The answers to those questions are just the start of a list of things to consider, according to Dr. Stephen O’Grady, farrier, and equine veterinarian. The member of the International Equine Veterinarians Hall Of Fame from Marshall, VA., makes it pretty clear that while he feels there may be many situations when raising the heels is beneficial , there are a lot of other times when farriers and equine veterinarians use the practice when it should be avoided.
The Good and The Bad
Raising heels can have some positive effects in therapeutic cases — research indicates it can move the ground reaction force back toward the heels, can decrease the stresses on the deep digital flexor tendon and may ease pressure on the navicular bursa/bone. But O’Grady says it is also important to realize that raising the heels may have side effects — often detrimental ones.
O’Grady says the technique is often used to deal with low or under-run heels — often to the detriment of the horse.
The goal may be a positive one — to restore the proper hoof-pastern axis when appropriate. But the method involves placing additional pressure on structures that are already under stress, compromised — and may have actually failed altogether.
“In reality when dealing with low heels, extending or elevating the heels is maintaining the alignment of the hoof- pastern axis and supporting the deep digital flexor tendon,” says O’Grady, “but increasing the load on the heels, thereby increases the propensity that it will cause further damage, they will deform and it decreases their growth due to the increased pressure. Most actions used to provide support involve movement of the center of pressure.”
The Importance of Structure
In the case of extremely low heels or under-run heels, wedging heels places the load onto the soft tissue structures that are already compromised .
“The whole concept of heel elevation depends on the structures,” O’ Grady says. “If the structures — the heel base (hoof wall, bars, and buttress) — aren’t there or are extremely damaged, you’re transferring force to the soft tissue structures that can’t handle it.”
This is particularly true of under-run heels.
“With under-run heels, you have lost these structures,” he says. “The bars are broken down or crushed and the hoof wall is curling underneath. Raising the heels in this situation may be contraindicated as the structures are severely damaged and have no more ability to accept weight. If you increase the pressure on them by adding a wedge, you will damage them even more.”
If the structures are present and raising the heels makes sense for what you are trying to accomplish , O’Grady feels most of the accepted methods — wedge pads, shoes with swelled heel, heart bar shoe, etc., — will work. He says he is had success recently using impression material across the bottom of the back of the foot at the heels and then placing a shoe with a wedge insert or a heel plate into the deformable material. . In the case of low heels, he’s found placing the horse in a wooden shoe for a period of time has helped if any re-growth of the heels is possible. Another simple method to improve the heels is to remove the shoes and allow the horse to be barefoot for a brief period of time with controlled exercise in deformable footing.
“But it all depends on the structures,” he emphasizes again. “If the structures are not there, often the best thing to do is leave it alone.”
O’Grady notes that a heart bar shoe, for instance, is not helpful if you do not have enough frog size/mass in which to transfer the load. And the presence of the negative palmer angle you are trying to correct may very well mean the structures you want to rely on are not going to be in any shape to help you. As O’Grady described in Adams Lameness in Horses, a negative palmar angle, “basically means that the soft tissue structures (frog, digital cushion) have decreased in mass due to damage and / or they have prolapsed palmarly. This type of hoof conformation alters the mechanics of the foot as the compromised heels lost both the ability to accept weight and to dissipate the energy of impact.”
A Minimalist Approach
Sometimes, there will be little, or even nothing, a farrier can do to correct this kind of problem. O’Grady notes that many Thoroughbreds are born with poor feet due to genetics, and such horses will always be maintenance cases. And even on horses born with good conformation, problems with low or under-run heels may have been allowed to progress to a point where a farrier will be able to offer little help.
“All living organisms are born with structures that have a certain amount of ability to restore or re-grow ,” O’Grady says. “But you can reach a point where those structures will lose their ability to re-grow. The center or dermis they grow from is damaged to a point where it no longer functions.
If that has happened to a horse you are providing hoof care for, your best efforts are probably going to be ineffective .
“If you lose the digital cushion, it’s gone,” O’Grady says. “You can’t make it better.”
So, what should a farrier do in these situations?
“With a broken backward hoof-pastern axis, if you don’t have the structures you need to raise the heels, it may be sufficient to reduce the length of toe, increase the ground surface at the heels if possible and protect what you have in the heels,” advises O’Grady.
If possible, it is best to prevent this type of problem before it progresses too far. While you cannot do anything about a horse’s genetic makeup, O’ Grady believes that understanding the function of the foot and applying appropriate farriery techniques can prevent a lot of low-heel problems.
O’Grady frequently can be heard saying, “It’s the trim, stupid” — a phrase he credits to Dr. Andy Parks, an International Equine Veterinarian Hall of Fame member who is a surgeon on the faculty at the Veterinary School at the University of Georgia. And while many farriers also maintain that trimming is the most important part of hoof care, there is a great deal of disagreement about what constitutes proper trimming — particularly as it concerns the palmar aspect of the foot.
“It is quite straight forward to trim the toe and quarters,” O’Grady says. “But when you start trimming the heels, there are many different traditions, concepts and theories.
O’Grady says it is important to keep the different roles of the toes / quarters and heels in mind while still considering the foot as a whole. The dorsal section of the foot — the bone, laminar interface, and hoof wall — is static and accepts weight, while the palmar foot is dynamic and contains the soft tissue structures that absorb concussion and dissipate the energy of impact. Both functions need to be inter-related, and all the structures need to be contained within the hoof capsule. It this manner, the soft tissue structures in the palmar section of the foot have the ability to share some of the weight bearing function.
O’Grady points out that with severely low or under-run heels, the resulting negative palmar angle and the increased load placed in this area may cause the soft structures to migrate even further palmarly, until they wind up beyond the back end of the hoof capsule. If that happens, any attempt to transfer weight to those structures will result in even more damage.
“There are no easy answers to this problem,” he says. “You have to keep asking yourself, ‘Do I have the structures to anatomically and mechanically do what I want without causing a negative side effect?’ If you don’t you can wind up with a situation that’s worse than the one, you’re trying to correct.”
A foot shod with a heel wedge. The red arrow is the middle of the foot. The yellow arrow points to the end of the hoof walls at the heels. The green arrow points to the broken forward foot-pastern axis caused by elevating the heels. The blue arrow points to the horizontal position of the coronary band above the heels. The white arrow points to where the wedge pad is placing pressure on the soft tissue structures, beyond the end of the heels.
In a case of under-run heels like these, the heel structures such as the bars and hoof wall have already failed, meaning they are no longer capable of bearing weight. Note that weight bearing is no placed on the frog and it is migrating palmarly.
Heels are sometimes wedged to attempt to correct a broken back hoof pastern axis such as this one, but doing so can put additional pressure on already damaged structures. In this photo, note the even hoof wall growth below the coronet from the toe to the heel indicating the soft tissue structures are still intact.