Hoof bars are often under-appreciated. Discover how this crucial part of your horse’s feet affects his soundness and well being.
The hoof is commonly considered one of the most important parts of equine anatomy. Yet there’s still a lot of research going on about the full scope and function of the hoof and its individual components.
The back of the hoof is generally understood to be for shock absorption, energy dissipation and vertical support, while the front is primarily designed for protection, traction and impulsion. When seen in cross section, the coffin bone forms the foundation for the front of the hoof, and the softer tissues of the lateral cartilages and digital cushion and frog form the foundation for the back.
Most riders understand that the hoof expands and contracts upon impact and acts as a mechanical pump for all bloodflow below the knee/hock joints and throughout the hoof (yes, the internal hoof structure is extremely vascular!). We also accept that the wall acts as protection for the internal structures, the frog provides traction and sensory information, and the sole protects the bottom of the hoof.
But how much does the average horse person know about the actual function of hoof bars?
Form and Function
Hoof bars are the “turning point” of the outer wall at the back of the foot by the heel bulbs. They offer structure, support and movement for the hoof. In fact, the bars are actually a continuation of the outer wall and the white line that grows “inside” the hoof and extends from the heel buttress to approximately halfway down the frog, towards the apex. They are considered the “break” in the solid hoof wall cylinder that allows for flexibility and optimum hoof mechanics. Hoof bars support the back part of the hoof, enable it to expand upon impact, dissipate energy to the lateral cartilages and the digital cushion, and ensure the hoof stops descending. All rather crucial functions of a healthy hoof!
Being part of the hoof wall, the bars are also subject to the same wear and exfoliation as the outer layer, and should be addressed as such. According to some trimming philosophies, bars left too high have often been implicated as a contributing factor in navicular syndrome, while bars trimmed too short have been associated with weak and collapsed heels. Most trimmers and farriers acknowledge there is no “standard” when trimming the bars – or the entire hoof — and that the whole horse, his environment, and the current condition of the internal structures need to be taken into account. It is not as simple as applying a standard rule to each hoof.
A Trim for All Seasons
The specifics of various trimming methods are beyond the scope of this article, but let’s review some of the commonly agreed upon viewpoints.
Studies by Robert Bowker, VMD, PhD, suggest that peripheral loading of the hoof (i.e. the wall being the primary or sole support to the entire foot) is not a natural function as it “suspends” the horse solely from the laminae connection and can contribute to its failure. Rather, the weight-bearing role is now more commonly understood to be distributed and shared among the wall, sole, frog and bars of a healthy hoof. As hoof shape, growth and wear respond directly to the environment any given horse lives on, it stands to reason that the hoof itself and the supporting hoof bars also change shape from season to season.
Consider the impact on the hooves of a horse living 24/7 in a soft sand summer paddock, and one living on frozen ground during the winter months. On softer footing, a nicely concave hoof with recessed bars would sink into the ground and load bearing would be shared by all components as the footing “fills” the hoof from below. Put the same hoof on hard flat terrain, however, and you would lose any support the shorter bars could offer, as they would now be “suspended” high in the concavity of the hoof capsule. While hoof bars need to be recessed sufficiently in order to be able to descend upon impact, they also need to be able to “bottom out” to provide optimum vertical support upon impact. Not acknowledging the varying requirements of the hoof depending on season and footing, and trimming accordingly, may often contribute to “mystery” lameness during seasonal changes.
Common Hoof Bar Pathologies
Hoof bars tend to grow faster than the rest of the hoof wall capsule, and the bar laminae are responsible for producing both bar material and much of the entire sole of the horse. At times, one sees a thin-soled horse with heavy ridges of sole material that begin at the end of the bar (halfway along the frog) and extend down alongside the frog, at times wrapping completely around the apex. This is sole material “travelling” along the foot on its way to building a toe callus at the front of the hoof, to provide protection and support under the tip of the coffin bone. These ridges are usually “put down” by the hoof to provide interim support to the center of the hoof when the environment or a hoof pathology does not allow for normal support or function. Some farriers/ trimmers consider this “excess bar material” and routinely trim it away, much to the detriment of the hoof and the horse’s comfort!
A healthy hoof with properly weighted and worn hoof bars will rarely need to have the bars trimmed, as they exfoliate just like the rest of the wall does, to a level just above the sole. However, when the back of the hoof is compromised (weak internal structures, improper hoof balance, etc.), the bars may not function as they should and actually collapse under the weight of the horse. “Laid over bars” will not wear properly and will continue to grow, essentially growing over the sole or even impacting into it. This undue pressure damages the sole corium, affecting its growth, and is a major cause for abscesses in the heel buttress — notoriously difficult to diagnose and treat at that location!
Equine guardians are encouraged to understand the basic anatomy of the hoof, the biomechanics of their horses’ gaits, and how movement, environment and trimming can affect hooves. Hoof bars are an often ignored and underrated part of the hoof, yet they serve a crucial role in its overall health and function. With a little knowledge and the assistance of a qualified hoof care professional, the bars can be maintained or rehabilitated to their proper function, and in essence require little maintenance during regular trims.
Johanna Neuteboom is a professional barefoot trimmer and certified equine sports mass age therapist. Her company, Barnboots.ca offers services dedicated to holistic horse care, resources and networking, educational exploration and select equine adventures. She shares her life with her five-year-old Friesian mare, the half brother of the same age and his owner, and lives in the Muskoka region of Ontario. For more information on her services and other clinics and workshops, please visit the website: barnboots.ca