Various aspects of barefoot methodology relevant to farriery in equine veterinary practice

Stephen E. O'Grady, DVM, MRCVS

Virginia Therapeutic Farriery, Keswick, Virginia, USA.
Corresponding author email: sogrady@look.net

Summary
 

The structures of the equine foot have the unique ability to adapt, change shape and restore. There are multiple benfits in shod vs. barefoot or in allowing the horse to be without shoes for a given time period to improve the palmar section of the foot. However, it requires a transition period, a change in the manner in which the foot is trimmed, a commitment from the owner/trainer and, in the case of leaving the horse without shoes permanently, it depends whether the horse can perform the desired function without shoes.

Introduction

The equine foot with healthy structures is superior in its natural or barefoot state as opposed to the shod state with regards to accepting the weight of the horse, shock absorption and dissipating the energy of impact (Davies 2007). Furthermore, the structures of the foot have an inherent ability to change and improve over time by the process of adaptation (Davies 2007). Shoes are applied to the horse's foot for a number of reasons: protection when wear on the ground surface of the foot exceeds growth at the coronet; maintaining or enhancing functionality such as traction; and as a therapeutic aid to improve the structures of the foot and treat lameness. The use of traditional farriery or the application of a shoe with regards to the elite athlete or competition horse is necessary but recently much of the approach to traditional hoof care by veterinarians and farriers has been challenged by barefoot proponents (Balch et al. 2003; Balch 2007). This is not to infer that traditional farriery is not performed and continues to be performed in a proper physiological manner with minimal damage to the horse's foot (O'Grady and Poupard 2003; O'Grady 2008, 2009). However there are some aspects of the barefoot methodology that could be applied to traditional farriery and may warrant consideration. There are less rigorous competitive disciplines or athletic endeavours and pleasure horses that may permit a horse to perform and remain sound without shoes if an appropriate adaptation period is allowed. The author has been successful in improving the structures of the hoof capsule in the palmar section of the foot in a growing number of horses by leaving the horse barefoot for a period of time. Finally, if a horse is being rehabilitated due to disease or injury, it appears prudent to remove the shoes during this period of recuperation as the health, structures and conformation of the foot are likely to improve. A successful outcome with the situations outlined above appears to require a different approach to trimming the foot.

 

Fig. 1.

Fig 1: Red arrow shows the first interface between the hoof and the shoe. The blue arrow shows the second interface between the shoe and the ground.

Fig. 2.

Fig 2: The toe and quarters are static (red arrow) while the hoof wall at the heels moves against the shoe (yellow circle).

The effect of applying a horseshoe

There is little doubt that applying a horseshoe to a horse's foot will not change the density and the functionality of the hoof structures. A brief look at the effects of applying a shoe may highlight the potential benefits of being left barefoot or left barefoot for a brief time. In actuality, the horseshoe is not an extension of the horse's foot. Placing a horseshoe with different properties than the hoof capsule between the hoof and the ground replaces a single interface with 2 interfaces (Fig 1) (Parks 2011; Eliashar 2012). This change in interface will invariably have consequences on foot function. This interface alters the concussion-dampening effect on the lower limb, which results in an increase of impact intensity on the hoof (Benoit et al. 1993; Roepstorff et al. 1999). Placing a shoe elevates the hoof off the ground surface by loading the hoof wall; this elevation results in less heel expansion compared with the unshod foot (Roepstorff et al. 2001). Glued aluminium shoes restrict heel movement even further and potentially interfere with shock absorption (Yoshihara et al. 2010). The process of hoof growth and wear will often allow the barefoot horse to maintain the shape of its feet as friction and thus wear occurs between the ground and the entire solar surface of the foot. When a horse is shod, friction occurs between the expanding heel of the hoof capsule and the shoe which induces greater wear at the heel compared with wear at the toe which, over time, will change the conformation of the foot (Fig 2) (Moleman et al. 2006).

Method
The Trim

 

Fig. 3.

Fig 3: Nippers being used at a vertical angle starting the cut dorsal to the sole-wall junction. This will create a thin mound of hoof wall around the perimeter of the foot.

The trim applied to a foot that is to be barefoot should be different from the trim applied to a foot prior to being shod. In the author's farriery practice, the difference in the trim is described as 'when the horse is to be shod, the foot is trimmed; when the horse is to be left barefoot, the foot is shaped'. The biggest difference is that the horny sole is left intact and the hoof wall is left 3-5 mm longer for as much protection as possible (O'Grady 2011; Castelijns 2012). The solar surface of the foot is initially brushed briskly with a wire brush. The hoof knife is generally not used in the barefoot trim or shaping other than to remove any extraneous, exfoliating horny tissue from the frog. If there is excessive hoof wall to be removed, hoof nippers will be used but not in the usual fashion of cutting horn on the same horizontal plane as the sole. Instead, the nippers are placed in a semivertical position at an angle of approximately 45° and the cut is started on the outer side of the sole wall junction (white line) (Fig 3). The goal is to bevel the bearing surface of the hoof wall. A rasp is used to trim the heels of the hoof capsule in a horizontal direction across the frog just to the point where the heels are on the same plane as the frog, which makes the palmar section of the foot 'load sharing'. This will generally place the heels on the solar surface of the hoof capsule at the widest part of the frog. Starting at the heel quarter, the rasp is also used in a vertical direction at a 45° angle around the circumference of the foot staying on the outer side of the sole-wall junction (Fig 4). This will create a sharp edge at the lower end of the bevel that is removed by rasping this sharp edge in a horizontal direction, resulting in a rounded edge of at least half the thickness of the hoof wall (Fig 5).

Fig. 4.

Fig 4: Rasp being used on a vertical angle dorsal to the solewall junction. Note the amount of hoof wall (3–5 mm) being formed at the perimeter of the foot.

Excessive hoof wall flares are removed from the outer hoof wall; then the rasp is used to blend this area into the rounded perimeter of the hoof wall. Horses that have worn shoes for any considerable length of time are likely to have some degree of hoof wall separation between the toe and heel quarters. If the toe and heel structures on the ground surface of the foot are intact and strong, these separations can easily be removed by placing the rasp at a more acute vertical angle and removing the separated outer hoof wall down to where the sole-wall junction becomes solid. The toe and heel structures are able to accept the weightbearing function and the quarters will grow out solid (Fig 6). Finally, in order to appreciate the sole thickness, hoof testers are placed on the sole dorsal to the apex of the frog. If the sole does not deform, breakover can be enhanced by creating a slight bevel with a rasp starting half way between the apex of the frog and the newly created perimeter of the hoof wall.If successful, with the foot on the ground, a space will be present under the dorsal toe to which a credit card could be placed underneath the toe. This trim can be modified according to the amount of horn present or the conformation of the foot. Trimming (bevelling) the bearing surface of the wall in this manner is also likely to prevent chipping and cracking of the outer surface of the hoof wall.

Fig. 5.

Fig 5: a) shows the sharp edge created when using the rasp vertically. b) shows the thick rounded perimeter created by using the rasp in a horizontal direction to remove the sharp edge.

Fig. 6.

Fig 6: Foot shaped to remain barefoot. In a) note the separations between the toe and heel quarters. Separations are removed in b) using a rasp at a steep angle trimmed to a solid sole-wall junction

The transition from shod to barefoot

Horse owners are confronted with the purported benefits of leaving a horse barefoot by their equine care providers, equine lay publications, barefoot proponents and the Internet. Furthermore, the deleterious effects of various aspects of farriery have led to a resurgence of interest in maintaining horses barefoot with the appropriate trimming. There are many factors/variables to be considered in making the decision as to whether a horse is a candidate to leave barefoot. These may include the type and amount of work expected of the horse, surface on which the horse works, genetics, hoof conformation, the integrity and strength of the palmar foot and the present condition/health of the structures of the hoof capsule. The degree of involvement of any one of these factors or a combination of these factors may make the horse not amendable to remain barefoot. It must be remembered that when the horse wears shoes, the hoof is raised off the ground and the major load is placed on the hoof wall. Being above ground, the sole-wall junction, the sole, bars, digital cushion and frog will lose their normal degree of structural integrity and density from lack of stimulation due to the interface created by the shoe. The sole thickness will invariably decrease with shoes, thus limiting its protective nature. The structures of the hoof capsule have the ability to change density through the process of adaptation; therefore an adequate transition period for adaptation of the foot is essential when attempting to change from shoes to barefoot is logical (Eliashar 2012). If the hoof walls are thin and of poor consistency and if the sole at the toe markedly deforms when hoof testers are applied, this animal will be a challenge to convert to the barefoot state. The shoes are removed and the feet are trimmed as described above emphasising that no horn is removed from the solar surface of the foot; the hoof wall and frog at the heels are trimmed to the same plane using the rasp in a horizontal direction and the remainder of the trimming is performed in a vertical direction starting on the outer side of the sole-wall junction. The author recommends that following the trim the horse be walked one or 2 times a day (15-20 min) on a firm surface for 7-10 days. If the horse remains comfortable, the horse may be turned out in a small area (paddock or round pen) for a few hours daily for the next few weeks at which time, if sound, the horse can be turned out in a larger area for a greater amount of time. The feet are trimmed (shaped) at 3-4 week intervals as outlined in the trim protocol above being sure to keep the hoof wall at the heels and the frog on the same plane. The transition period will depend on the condition of the feet but generally 60-90 days are necessary and recommended before the horse should begin some form of exercise.

Using barefoot methodology to improve the palmar section of the foot

 

Fig. 7.

Fig 7: Long toe-under run heel foot conformation with the frog located distal to the level of the hoof wall at the heels. Note the horse standing on the frog when the shoe is removed and the space created under the hoof wall at the heels

The hoof capsule with low or under run heels and a negative angle of the solar border of the distal phalanx is a significant and not unusual problem. There are many farriery techniques described to address this type of hoof conformation yet none that have shown consistent documented success. If the heels are allowed to grow forward, the surface area on the ground surface of the foot is decreased which places more load on less heel area that is now located dorsal to the base of the frog. More weightbearing on less surface area decreases heel growth further and continues to compromise the structures of the heel. The frog is now situated palmar to the heels of the hoof capsule and descends between the branches of the shoe 'looking' for the ground in an attempt to assume some load. This is complicated by the heels of the hoof capsule expanding against the surface of the shoe, which abrades/wears the horn at the heels further. The author has been able to improve the heels' structures significantly in a number of cases by taking the horse out of work and giving them time off without their shoes. The shoes are removed and the feet trimmed as outlined in the trim protocol above with a few exceptions. When shoes are removed from a horse with under run heels, the frog will often be situated below the level of the hoof wall to the extent that when the foot is placed on the ground, the horse will be standing on his frog alone (Figs 7 and 8).

Fig. 8.

Fig 8: a) denotes foot conformation with a long toe-under run heel conformation. b) shows the frog located below the level of the hoof wall when the shoe is removed.

Fig. 9.

Fig 9: Frog plate cut from a 2° wedge pad and secured in place with small horseshoe nails at the toe.

The first objective is to get the frog and the hoof wall on the same plane so this section of the foot is 'load sharing'. This can be readily accomplished without shoes by placing a frog plate beneath the frog for 24-48 h and standing the horse on a firm surface or this can be accomplished by the sheer weight of the horse during the first week of having the shoes removed (Fig 9). When the shoes are removed, the palmar section of the foot is left untouched as the frog will generally be located distal to the hoof wall as described above. A line is drawn across the widest part of the foot and excessive toe length is reduced by using the hoof nippers across the toe in a completely vertical direction (Fig 10). The remainder of the hoof wall is rasped on an angle as previously described. The management of the horse is handled as described for the transition to the barefoot state. The foot is trimmed at 3 week intervals and, at the second trim, the hoof wall and the frog will generally be on the same plane with the heels of the hoof capsule beginning to restore. Thus it is likely that the heels can be rasped in a horizontal direction, i.e. the same plane as the solar surface of the foot and by the second trim, the bars and angle of the sole will become apparent (Fig 11).Hopefully the integrity of the hoof wall will improve and the sole thickness will increase; both of which can be verified with hoof testers or radiographs. The amount of time the horse is without shoes is decided by the owner/trainer and clinician but the author recommends 60-90 days if possible. When shoes are replaced, strict attention is paid to the trim, size type and placement of the shoe using guidelines such as the hoof-pastern axis, the centre of rotation and trimming to the base of the frog or to the same plane of the frog (O'Grady 2009).

Fig. 11.

Fig 11: a) is the foot illustrated in Fig 8b and Fig 10 at 3 weeks post shoe removal and b) is the same foot at 6 weeks post shoe removal and additionally shows the horny sole at the angle of the sole to be solid (red arrow).

Conclusions

The structures of the equine foot have the unique ability to adapt, change shape and restore. There are multiple benefits in shod vs. barefoot or in allowing the horse to be without shoes for a given time period to improve the palmar foot. However, it requires a transition period, a commitment from the owner/trainer and in the case of leaving the horse without shoes, it depends whether the horse can perform the desired function without shoes. Removing the horse's shoes without a transition period and the appropriate foot care will seldom be successful as the structures need time to adapt to being able to accept weight without the protection of shoes.
It is thought that palmar foot pain is an often encountered cause of lameness seen in the horses. Furthermore, it is likely that farriery will be part of the overall treatment regimen. Compromised structures in the palmar section of the foot often lead to a negative angle of the solar border of the distal phalanx. It has been reported that every 1° decrease in palmar angle of the distal phalanx results in a 4% increase in peak force on the navicular bone (Eliashar et al. 2004). The frog being situated distal to the level of the hoof wall at the heels is often correlated with this negative angle of the distal phalanx. The author is not aware of any proposed farriery method more effective in repositioning the frog and the hoof wall on the same plane as allowing the horse to remain barefoot for a brief (determined on a case by case basis) interval of time.

Author's declaration of interests

No conflicts of interest have been declared.

Ethical animal research

All work done in the author's practice under acceptable standard of care guidelines.

Source of funding

None.

References

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