Expanding on Expansion, Hoof Function

A new twist on things.

It's not about going barefoot or being shod.

            Ever since someone decided horseshoes were a necessary evil, the debate over their effect on foot function has raged. Those advocating barefoot for the better of the horse, claim that horseshoes do not allow for expansion and contraction, resulting in a loss of foot function (read circulation), while those nailing on horseshoes loudly proclaim that expansion and contraction is not impaired, as nails should never be place behind the widest part of the hoof.

Several hundred articles and even a scarce few scientific papers have been produced to support the belief that horseshoes could be applied in a way that did not inhibit hoof expansion and contraction.

            Let me present a new twist on foot function that cast a stone upon the water, a stone that could, and should result in a tsunami.

            Expansion and Contraction are not enough. "Nearly all-new research into the functions of the frog, lateral cartilage, and digital cushion are flawed." This is a bold statement, but one that can be easily proven.

            Over the last decade there have been several papers published on the function of the digital cushion, and its function during footfall, and its relationship to overall foot function. In each of these papers the importance of frog contact with the ground has been stressed, or somehow referred to. Nowhere in theses studies has the importance of frog anatomical function been clearly defined. What am I talking about? The anatomy of the proximal internal frog surface (the surface that makes contact with the digital cushion), and the structure defined as the frog’s spine. As a horse person you may be more familiar with, and identify with its ground surface counterpart, the central sulcus, often seen as a deep crevice in the back, center of the frog.

            Our studies are proving that the health of the frog’s spine is crucial to the overall health of the caudal aspect (back half) of the horse’s foot. 

            The attached picture shows a healthy frog spine, and how distal and proximal (up and down) movement of the heels cause it to move either laterally or medially, directing the downward forces to the appropriate heel bulb and cartilage.

This action results in the correct distribution of pressure and force occurring at impact. This action is also responsible for directing the stimulus needed for correct growth of the heels, bars, digital cushion, and cartilage of the foot. When distortion of the hoof capsule is limited to expansion and contraction only, the frog spine remains centered and the forces created by the downward movement of the pastern and deep digital flexor tendon cannot be distributed to the advantage of the foot. Simply stated; expansion and contraction is not enough, the foot needs to be able to distort on all dimensions.

            Simply removing the ridgid horseshoe may be a step in the right direction (provided stability exist), but how the frog is addressed during the trimming process is of greater importance. A weak or unhealthy frog results in the foot’s inability to deal with force. A deep central sulcus is unhealthy, and is evidence of a weak spine (instability), the direct result of a lack of correct stimulus. Correct pressure is the stimulus for correct growth, and only with its application can the frog, and its spine become healthy. It is now clear that simply applying pressure to the frog is not enough to achieve true foot function, or a healthy frog for that matter. Dental impression materials, frog wedge pads, and any other attempt to apply pressure to the frog in a foot that can only expand and contract will not result in correct frog growth. We need to know how to apply the correct amount of pressure to the frog and heels, while allowing the foot to distort on all planes. The frog then becomes the vehicle for the distribution of energies to the back half of the foot.

            There is a simple protocol for treating an unhealthy frog, and helping your horse develop a strong frog spine. It involves treating any infection that might be evidenced in the central sulcus, the deeper the central sulcus the weaker the frog’s spine.  I suggest infection be treated with a non-necrotizing treatment (those that will not damage healthy tissue), Silvetrasol Hoof and Wound Wash is one such product. The frog should be trimmed by removing all dead or exfoliating horn, working to center it on the centerline of the foot. It is best to trim a slight angle to the sides of the frog, following its contour. This helps in distributing needed pressure to the correct underlying structures, resulting in healthy spine growth. You will then need to exercise the horse, exposing its feet and frogs to the proper environment (provided the hoof is stable enough), turnout is not enough. Hand walking a horse over uneven ground will cause the foot to distort, working the frog spine. Be sure to evaluate the frog and the health of the horse’s foot before you begin, a very weak foot cannot cope with excessive amounts of distortion. In such cases, you will need to work slowly, exposing the foot to less distortion in the beginning, increasing the work with the steady return of health to the frog, its spine, and to the stabilization of the caudal (back) foot. In cases where stability is in question it may be necessary to provide dynamic stability (stability by means of materials with elastic potential) by using Perfect Hoof Wear or a spring steel type of shoe.  Flexible horseshoes do not provide stability and often glue on shoes are too immobilizing, causing restrictions, which result in incorrect distortion.

            There you have it, expansion and contraction are not enough, and the argument that the conventional horseshoe when applied correctly allows for it, is no longer a valid argument. Foot function is complex, and the current trend of being “complacent with simplicity” can no longer be tolerated, not if our intentions are to serve today’s horse best. True foot function requires multi-dimensional distortion and dynamic stability, not simply expansion and contraction. The argument that the conventional horseshoe, dental impression materials, frog pads, or the host of other devices developed as a result of such beliefs support true foot function, is in my judgment no longer a valid one.

            For more of the latest information on foot function, please visit our website: www.equinepodiatry.com