This debate is often fiercely contested and remains controversial with two schools of thought, traditionally diametrically opposed. As the author continues on the never-ending journey into understanding the hoof, one thing has become clear, barefoot is best, but yet another paradoxical realisation has occurred simultaneously, shoes are a necessary reality. The miracle of nature that is the hoof is designed to move and flex, protecting the inner structures while deforming enough to absorb cyclic concussion, renew itself and act as a sensory organ. So why do we put shoes on it, and do we ever need to?
One of the biggest factors in this debate is hoof function. The systems of the hoof are designed for being bare, to share load, protect, nourish and wear. Apart from adding increased protection, application of a perimeter fit shoe diminishes these functions.
Fig.1 The Haemodynamic system uses the structures of the hoof to manipulate blood flow within the hoof, creating a hydraulic dampening effect. Bowker (2003). Radiograph by Dr Randy Eggleston.
The haemodynamic system works most efficiently when the heels, bars, and frog are on the same plane and with the sole working in unity to dissipate the forces of locomotion. Not just because of their simultaneous impact, but because of their integral composition.
Fig.2 With the Application of a shoe the impact load share of all the caudal structures is negated and there is inefficient use of the haemodynamic system.
The shoe lifts the hoof off the ground, the frog now has to descend through the shoe in order to make contact with the ground and become part of the wider system, this could lead to its eventual prolapse. In the meantime the heels are bearing all of the load, some thing they are not designed to do and run the risk of exceeding their elastic modulus and failing. Of course this can happen with hoof growth on a barefoot, but a bare foot is constantly being worn away, mitigating some of the growth, some barefoot horses require very occasional intervention if their hoof growth and hoof wear cancel each other out. In a shod foot the growth is protected and from the moment the foot is put down after being shod it gets worse until the day it is shod again. Roepstorff (2001) compared the expansion and contraction of barefoot vs shod and found that expansion and contraction was substantially reduced in the shod foot, possibly in part attributed to the reduced function of the haemodynamic system, he did however find that with the application of frog support padding expansion was returned to near barefoot proportions, but contraction was not, further research would need to be made to understand the implications of reduced contraction. This shows us that modern farriery techniques can help to restore function but still can’t fully replicate natural mechanics.
A point to expand on is that as soon as the foot is shod, protected hoof growth, through the shoeing cycle, has a direct effect on morphology and therefore biomechanical influences. Van Heel et al (2004,2005) and Moleman et al (2006) showed how through a shoeing cycle, hoof growth reduced the angle of the hoof, increased the load on the Navicular apparatus and affected hoof unrollment (Fig.3).
What must be understood however is that a barefoot will suffer the same deformation, if it does not receive enough work and/or trimming intervention to maintain proportions of the foot and contact of the solar structures. The forward migration of the heels in hoof growth also means that they become positioned under the wings of the distal phalanx rather than under the haemodynamic system. This transfers impact forces onto the bone rather than the soft tissues designed to absorb them also predisposing the heels to exceeding their elastic modulus. But again, this will also happen in a poorly managed barefoot.
A recent study (Malone and Davies 2019) studied some morphological effects of barefoot vs shod over a 7 week period. Finding that proximal hoof circumference decreased more significantly in the shod foot, hoof angle increased in the barefoot compared to its decrease in the shod foot, sole length decreased in the bare foot and solar circumference increased in the barefoot. This study echoed the findings of Clayton et al (2011) which concluded that barefoot trimming resulted in elevation of the heel angle and solar angle of the distal phalanx. These findings point toward more positive morphology from being barefoot, something which correlates with the experiential opinion of the author. Proske et al (2017) found altered locomotion in shod horses vs barefoot horses while simultaneously finding increased digital cushion depth after a period of time in the barefoot, again indicating more optimal morphology of the barefoot. The study eluded to shoeing predisposing to lameness over time, understanding the physiological effects of reduced hoof angle and digital cushion depth, this would correlate with the findings of the papers stated earlier. Having said all of that, the author has also experienced positive morphology over time, when being shod, with appropriate shoeing cycles and frog support padding, so it must be said that application could always play a role in the findings of these studies. Forgetting morphology for a moment, other studies have quantified the effects of shoeing on impact forces showing higher landing velocities, higher peak forces and higher and longer impact vibrations (Willemen et al 1997, Roepstorff et al 1999, Parkes and Witte 2015). Modern techniques have sought to address this with the use of plastics, although these types of shoes showed more of a damping effect, less friction and slower shock absorption than steel shoes, they still didn’t replicate the barefoot (Back et al 2007).
So the question remains, if the hoof functions better, morphs better and has reduced concussive forces on it, barefoot, why do we need to shoe it?
Many people would argue that using hoof boots addresses the apparent need for shoeing. Firstly, boots also affected biomechanics by resulting in a prolonged stance time and time of braking force peak. Indicative of a slower deceleration phase during limb impact with the ground. Also, a prolonged deceleration phase of the stride and increased the sole length in contact with the ground (Fernando et al 2016). Secondly, the need for shoeing is not solely for protection when wear exceeds growth.
Without sounding insensitive we must appreciate that the domestic horse no longer lives by the rule of survival of the fittest. Horses reach adult hood with poor conformation, creating imbalanced forces on the hoof, leading to poor hoof conformation and feet that require shoes in order to create optimum load support and hoof ground interaction. The morphological effects on the hoof could come from seemingly abstract influences, pathological and/or human. Tack, feeding regime, riding ability, the humans own physiological dysfunctions, compensatory postures, surfaces! All play a role in biomechanics and biomechanics can directly affect hoof morphology. Unless you’re riding a perfectly conformed horse, perfectly balanced, bareback and bridle less, you are potentially having just as much effect on the physiological state and therefore the feet of the horse, as some steel nailed to the bottom.
Oosterlinck et al (2015) found that toed-in horses (Fig.4) had an increase in toe landings, predisposing to navicular and Curtis (1999, 2018) discussed the conformational influences on hoof morphology. The hoof is viscoelastic, it returns to shape within its elastic modulus, but also it will suffer plastic deformation from the forces acting upon it and conformation will directly affect those forces. Farriery intervention can become necessary when pathology or conformational faults cause plastic distortion or uneven excessive wear (Fig.4). Re-establishing a base that supports gravitational lines of load can become necessary in angular limb deformities (Fig.4). Creating improved balance, both medio-laterally and dorso-palmerly with shoeing, can become necessary when breaking cycles of pathology and hoof morphology. Optimising hoof ground interaction on soft surfaces often requires farriery intervention to reduce sinking, and then of course there are the equestrian sports that require increased grip and propulsion that require more then the barefoot.
Fig.4 Two examples of poorly conformed horses that perpetuate poor hoof morphology and pathology cycles without the intervention of farriery.
Just as shoes affecting the forces on the hoof can be a negative, if those forces are pathological, farriery can create more sympathetic forces and comfort. Forces can be manipulated positively, take Fig.4, barefoot the imbalanced forces on the limb predispose the animal to joint, bone and ligament injury, after shoeing the conformation and therefore forces have been manipulated into a more positive situation.
Another consideration is human demand, barefoot requires more detailed management and patience, facilities, appropriate diet, balanced work loads, different terrains, a life more closely mirroring their natural free roaming existence. Something many owners could not provide! Many horses will require a prolonged transition period and changes to routine in order to facilitate staying barefoot and in reality this may not be practical in professional settings, although in the authors opinion the transition period is well worth the end result in most cases outside of cases restricted by conformation or pathology.
The professional sport worlds of racing/polo/hunting etc will always struggle with staying barefoot, the increased traction and grip afforded the horses with shoes is far too beneficial and improves the safety of the sport. Top level dressage and other arena sports can also gain significant improvements in performance from shoes via the ability to manipulate the hoof-ground interactions, in reality a high proportion of the worlds top sports horses rely on top class shoeing as part of their winning formula.
There are modern applications though that are beginning to create perhaps more attractive applications more closely mirroring the barefoot. Formahoof for instance, allows protection without nails, replicating the uniform load share of the barefoot and has been widely used in the polo world with its added traction models. The racing world is notorious for creating poor feet, ex-racehorses often have weak, thin hoof structures and usually respond very well to going barefoot, that is if the owner can bare the transition period. Peel et al (2010) expressed a reduction in hoof angle as a result of gallop training, this is significant in understanding why “flat” feet are ubiquitous in the ex-race horse population, Labuschagne et al (2017) added to the power of this statement by indicating “flat feet” are a “typical presentation of thoroughbred feet”. Much of this can be attributed to the very early application of shoes to young racehorses. Before their haemodynamic mechanisms have had time to develop fully they are raised off the ground and pounded down the racetrack. The destructive effects of early and repetitive shoeing are recognised (Brown 2017), Derek Poupard at Hoofcast.com has gone some way to addressing the issue while still providing the necessary traction required for competitive racing.
Fig.5 Hoofcast system allows training in barefoot with quick and easy nail-less shoe application. This enables the best of both worlds, the foot is trained and remains bare for the majority of the time, a shoe is then attached just for races without invading the hoof wall with nails.
Conclusion
Many horses are shod for unsubstantiated reasons, very often because its what the “norm” is, what’s traditional or what peer pressure encourages. We can not deny that the hoof functions better barefoot, but also we must appreciate domestication and the demands of the human don’t always create environments conducive to a barefoot flourishing. Naturally the horses surviving to roam the prairies will be those conformationally sound enough to have a healthy relationship between their body and feet, otherwise they would die. farriery often becomes necessary when we are asking conformationally disordered horses to work harder than their free ancestors. But! As farriery continues to progress and accept that its job is to create the best physiological situation for the horse, it will look to protect where necessary while as closely replicating the barefoot as possible. Systems like the Hoofcast system, looking to use modern materials to utilise the best of both worlds warrant further research and development. What we should really look to create is unity and agreement of the currently opposed factions of hoof care, understanding what’s best and what’s necessary, not only of hoof care, but the factors that play a role in it. It shouldn’t be farriers vs barefoot trimmers, it should be what is the best for this horse at this time.
References
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•Bowker, 2003, Hemodynamic Flow Hypothesis for Energy Dissipation in the Equine Foot, Hoof Care and Lameness, issue 70
Clayton, Grey, Kaiser, Bowker, 2011, Effects of Barefoot Trimming on Hoof Morphology, Australian Vet Journal
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Shoeing the racehorse… after training
Published Online:13 Sep 2017https://doi.org/10.12968/eqhe.2017.37.21
A Cross-Sectional Survey of Forelimb Hoof Conformation and the Prevalence of Flat Feet in a Cohort of Thoroughbred Racehorses in New Zealand