To shoe or not to shoe is a debate that is coming or has come to a horse event near you. The aim of this paper is not to weigh in on either side of this debate, but rather to offer insight to those horse owners who may be considering a change in either direction.
In my years of practice as a farrier and as an equine veterinarian I have yet to come across any one doctrine of equine podiatry that proved infallible in every situation. The subtle complexities of the equine digit and its wide variations of disease process makes becoming an evangelist to any one doctrine a risky proposition, especially for the horse. For a hoof care program to be successful we must consider each horse as an individual and avoid dogmatic thinking so as not to paint ourselves into a corner. Over emphasis on the means just might cause us to overlook the fundamental ends of farriery, soundness and the maintenance of a strong and resilient hoof capsule that appears symmetrical and balanced.
The following are some of the warning signs that a hoof care program is less than effective: Asymmetries of the hoof capsule such as toe flares or one very upright side and one very flared side of the hoof wall, long toe or heel lengths, atrophied frogs, overgrown bars, persistent thrush or white line disease, thin and weak hoof walls prone to cracking, slow hoof growth, thin soles, stumbling, soreness over uneven footing or on downhill slopes and finally overt lameness. If this sounds familiar, it may be time for a change. Where do you go once you suspect a problem?
While there are many knowledgeable unlicensed hoof-care professionals, I believe that it is best to start by consulting a doctor of veterinary medicine who has experience or interest in equine podiatry. The farrier, (this term not excluding barefoot advocates), should be present at the initial consultation and a meaningful discussion can result in a plan suited for both horse and rider. Debate outside of this arena, unless accompanied by statistically sound data, should be considered speculative and taken with a grain of salt or over a cold beer.
That being said, I will make the following generalizations concerning the horseshoe. Conventional wisdom as well as current research supports the concept that environmental stresses more than any other factor influence hoof quality. It can be said that the hoof, like many other biological systems, is subject to the vernacular of “use it or lose it.” For a hoof to be all it can be it must be kept balanced (a subject in and of itself) and it must be “exercised.” For example, ranchers who wanted to maintain good hooves would put feed and water at opposite ends of a rough arroyo, forcing their unshod horses to exercise and maintain nearly ideal hooves. The hoof is tremendously adaptable as evidenced by the horse’s ability to thrive in very diverse topographies. If left to their own devices a horse will maintain the ideal by moving only as far as their hooves will carry them through a specific terrain.
The horseshoe was developed as a means of protection for over “used” hooves. A working horse in rough country will wear a shoe in half at the toe in 2-3 weeks. This horse has two options, less work or some form of protection. In my experience, with good shoeing these working horses maintain excellent hooves and stay remarkably sound, even when the shoes are removed during the off season. However, a demographic shift in our horse population has taken place over the last 50-75 years. The show horse, the weekend warrior, the couch potato, and worst of all, the crippled brood mare, have replaced the workhorses of old. The modern performance horse likely lives in an environment that is not conducive to healthy hooves and yet performs at a level that demands normal hoof function. The reality that many of these horses’s face is that of under use and over protection of their hooves, the opposite scenario required for the production of the ideal hoof. There are a great many skilled farriers who rise every day to the challenge of maintaining soundness in these horses. Those who would be quick to criticize these dedicated professionals for applying horseshoes should try their hand at maintaining the hooves of fifty show jumpers for a couple years. This is quite simply a catch twenty-two.
There is often very little that can be done to improve a horse’s environment in relation to hoof health, therefore we usually have more control over the protection end of the equation. My approach to the before mentioned dilemma is to advocate a less is more position on hoof care. In other words, one should not lose site of the fact that the more artificial protection and support is provided to a hoof the weaker the hoof will become. This has become a very vicious cycle for many of our horses. Quite honestly, a good many owners and trainers are unwilling to give up the 4-6 mos it would take to rehabilitate some of these problems. So it goes until one day all the kings horses and all the kings men can’t put the hoof back together again. Well we usually can, but it might take a year.
The fact of the matter is, a horse that stands around in a wet and filthy stall will likely have weak and worthless feet. The horse that moves over even an acre or two has a better chance of maintaining good hoof quality. Finally, the horse that runs on several square miles or more of range country stands an excellent chance of having good hooves. While it is certainly true that genetics, conformation, farriery, diet, growth rate, injury, disease and a host of lesser factors all influence hoof quality. Many, including myself, recognize that the environmental factor is central to understanding how to manage horses that have good hooves. In other words, the obvious place to start when considering hoof care program is where does this horse live and what does the horse do for a living. A chapter of text could be written on the many possible answers to the preceding questions. In order to maintain focus, the environmental concept must be left at the following generalization. The stalled horse generally requires more thought and effort than does the range horse concerning hoof maintenance, no matter if the horse is shod or un-shod.
Concerning the hoof and horseshoe, let us frame our discussion within the context of a common paradox seen daily in clinical podiatry. That is how a horseshoe might injure a healthy hoof and then how a horseshoe might heal an injured hoof. Our generic healthy fore hoof has the following attributes. In appearance the hoof is symmetrical with a larger diameter at the ground than the coronet. The frog is large, healthy and makes contact with the ground on softer surfaces. The sole is a bit concaved, uniform in thickness and somewhat more viscoelastic than the walls. The toe is somewhat blunted at the point of break over and the hoof is smooth and burnished. Our unshod horse can trot soundly over a rocky road with the hoof efficiently damping over 1000 pounds of vertical force with each footfall. More than 80% of the concussive energy and load forces are dissipated by structures distal to the fetlock. This is accomplished by a combination of joint motion, the viscoelastic properties of the hoof, and by the hydraulic properties of the vasculature within the hoof itself.
If a steel keg shoe is applied to this hoof there will be a number of unfavorable consequences. The following effects assume that the shoe was applied in a correct, or to quote the in vogue term, “physiologic” manner. The horseshoe stabilizes the laminar connection between the hoof and coffin bone at the expense of an overall reduction in hoof expansion. The heel region will still expand and wear against the shoe, thereby altering the growth pattern. With virtually no wear at the toe and toe quarter the hoof will tend to run forward and develop a broken back, long toe/low heel conformation. The horseshoe increases braking forces at impact due to its less than favorable friction coefficient on most footing. Further more there is an increase in the frequency of vibrations within the shod foot as it strikes the ground as well as a maximization of the vertical ground force reaction. The horseshoe increases the pressure applied to the navicular bone by the deep flexor tendon as well as interferes with the hydraulic load damping mechanisms within the hoof. The rigid shoe does not allow the viscoelastic hoof to deform over uneven footing and therefore causes significantly more three-dimensional micro-displacements and jarring of the digit. The weight of the shoe increases animation but not stride length. Some advocates of the unshod horse mention a loss of pain sensation and a decrease in vascular perfusion as negative effects of the horseshoe. I am not aware of any research to document these phenomena. Discussions with experienced thermographers have led me to thus far conclude that a physiologic horseshoe does not significantly alter vascular perfusion and as for the masking of pain it is certainly minimal anesthesia if any at all. Never the less the combined effects of the preceding “evils” can be enough to create repetitive stresses that will exceed the capacities of the hoof tissues and lead to injury. As mentioned previously, many horses tolerate these ill effects and remain sound over a lifetime of wearing shoes. In my experience a leading cause of hoof-based injury can be traced back to extended periods of time spent in a “non-physiologic” horseshoe.
Every hoof has a state of optimal balance and as it drifts away from this condition the hoof does not function correctly. I believe that a hoof care providers skill can be measured by how closely and consistently they can approximate this state of optimum balance. As mentioned above, the horseshoe altars the normal wear pattern and leads to the hoof capsule running forward, resulting in excessive toe lengths. This problem can be by compounded by extended shoeing intervals (>5-6weeks), poor conformation, and by farriers that set shoes to far forward in relation to the center of rotation of the digit. Excessive toe lengths at a minimum will increase strain on the flexor tendons, the navicular structures, the dorsal lamina, and the coffin joint as well as detrimentally change the loading pattern of the hoof. Failure to recognize and correct for this factor will almost invariably result in injury of some degree. This is not a new concept, just one that is frequently forgotten.
The application of a horseshoe that is out of level or the application of a horseshoe to a hoof that is out of level can have profound consequences as the mistake is magnified over several shoeing intervals. A rigid shoe limits the hoofs ability to adapt and make adjustments to load asymmetries created by lateral/medial (outside/inside) imbalance. Evidence of chronic load asymmetries usually manifests in one side of the hoof being flared and the other side being very upright. Watch this horse walk over a firm level surface and you will generally see the flared side land first and the weight of the horse roll onto the upright or overloaded wall. In time this overloaded wall will begin a slow and enigmatic collapse which results in shear strain to the coffin joint, remodeling of the distal phalanx, retarded hoof growth, sub-mural bruising, sheared heels and a can of worms that can be complicated and costly to unravel. If left unchecked, this process often ends in osteoarthritis of the digit (articular ringbone).
In many cases the frog of the shod hoof atrophies and no longer performs its vital roll in the dissipation of energy. The reasons for this are not well understood to date. My simplistic view on the subject is that the shoe interferes with the frog’s normal interaction on the ground surface and if care is not taken to normalize this matter the frog simply wastes away. The hoof must be trimmed and the shoe fit in such a manner that the frog is subjected to its share of initial ground impact forces and weight. If this cannot be accomplished by trimming, artificial means must be employed to load the frog and maintain normal hoof physiology. As the shod hoof grows the frog is less likely to maintain ground contact. This situation is obviously exacerbated if the frog is not in the game when the shoes are initially applied. The frog serves as an intermediary between the ground and the structures within the hoof designed to absorb concussion, such as the unguanal cushion and collateral cartilages. If there is a disconnect between the frog and the ground, this energy will be transferred to structures within the hoof that are not designed to handle this type of shock. These tissues are overwhelmed and there is injury.
Aberrations in hoof balance and the loss of normal hoof mechanism due to frog inactivation are common sequela to non-physiologic horseshoeing. Use of undersized shoes, over-nailing, unnecessary protection with pads and bar shoes, overuse of traction devices and a host of lesser factors also contribute to the production of worthless hooves. Now consider our generic hoof has any number or combination of the following problems. The horse is lame at the trot with the shoes and lame at the walk without the shoes. Blocking the sensory nerves to the hoof with a local anethesthetic temporarily resolves the lameness. The hoof walls are thin, weak and breaking away at some of the nail sites. There is a quarter crack developing on the medial (inside) wall. This wall is upright, jammed at the coronet and sheared at the heel while the outside wall has a significant flare to it. The frog is elongated, thin and has a low-grade thrush problem. The heels might be over-grown and contracted or under run and crushed depending on the conformation of the horse. Radiology (x-rays) usually reveals some sort of degenerative change as well as some variation of imbalance between the hoof and bone structure. A scenario similar to this is presented to my practice multiple times every day. These horses usually have shoes on, but not always.
The goal is now to resolve the lameness and return the hoof to its healthy state. In most situations I prefer to use some variety of therapeutic shoe, at least initially. This statement is a generalization based on the average case. I have done work for devotees in both camps who keep horses that will not fully recover because of a refusal to remove shoes or apply shoes. Fortunately, these cases are uncommon and there are invariably multiple paths to recovery. Just as the horseshoe is capable driving the hoof out of balance, it is a powerful tool to be used in restoring balance. Details of these techniques are largely beyond the scope of this section. The horseshoe can offer significant mechanical advantage when attempting to ease break over and reduce toe lengths. The horseshoe can be used to elevate one side of the hoof and shift load away from a crushed wall as well as completely unload a portion of hoof. There are also a variety of methods by which a shoe can be used to promote frog function. Protection and support can be of benefit as well, but since our goal is a horse that can trot soundly over a rocky road without shoes, these methods must be employed on a very temporary basis or they only serve to weaken the hoof.
It is my hope that the circular nature of the preceding discussion would bring to light the idea that there is not an easy answer to the hoof care dilemma faced by most of our horses. Fortunately, there is a large body of research being conducted on a global scale in an effort to better understand the inner workings of the equine hoof. This flow of new information is cause for me to reconsider my stance on hoof care issues almost monthly it would seem. Sorting through this information can be frustrating for horse owners. My advice is first to consider the source of information and second to realize that hoof care is a result based endeavor. All any horse wants is a strong and resilient set of balanced hooves to walk on. There is accountability on the part of the owner, the farrier, and the veterinarian when this is not so. One final note of caution I would like to impart upon owners who have decided to remove shoes. Consider this a transitional endeavor and not something to be done cold turkey or without thought. For example, removing shoes during the heat of an Arizona summer is likely to result in heat founder. Shoes should be removed in more temperate seasons. Horses shod to the hilt with wedge pads, bar shoes etc should be stepped out of shoes gradually. First loose the pads then the bar shoes then the shoes. Horses in the throes of a laminitic episode must be treated with extreme caution on this front. The sudden reduction of laminar stability can be catastrophic. If shoes are going to be removed as a fix for a chronic lameness, this may or may not be in the horse’s best interest, consult a veterinary podiatrist for insight into your specific situation.
