How Does Footing Affect Dressage Horses' Soundness?
Dressage Today February 1998 By Dr. Hilary Clayton & Elizabeth Madlener

At a dressage show in the Midwest last summer, judges were complaining about the number of poor rides--so many stiff horses, no extensions, nothing to get very excited about. Yet at another show--this one in the Northwest--the judges were thrilled: It seemed that every horse that entered the ring was a good mover. It would be easy to surmise that at the latter show, correct dressage training was alive and well while at the former, it was floundering. The real difference? The footing.

Quality in dressage is measured by the horse's gait. "Freedom and regularity of the paces" is the minimum requirement, whether you are judging a prospect or scoring a test. Of the several factors involved in how well a dressage horse rates during any evaluation or how long he will hold up over the years of training, footing is a major consideration.

Obviously, this comes as no great revelation as we have compiled experiential data on our own, for ourselves. For instance, when we walk on ice, we take awkward, stilted steps. A march through heavy sand leads to early fatigue. Deep mud produces labored movement, while a trek on concrete can produce bone-jarring stiffness. Any sort of unusual surface causes a certain amount of constraint-- even abnormality--in our own posture and locomotion. It isn't much of a leap to extend this intuitive information to the plight of the horse when he is asked to perform as a gymnast on less than optimum footing. However, while anthropomorphizing is helpful, it won't serve entirely if we are to see to the well-being of the equine athletes. For accuracy, we need to investigate the specifics of the locomotion of the horse so that our well-meaning, but faulty, logic does not negatively affect his physical ability.

Biomechanical Considerations
During the impactphase of a step, the forward movement of a horse's leg is suddenly decelerated, causing a shock wave to travel up the leg. This shock wave is potentially damaging to the bones and joints of the leg, and is thought to be a major contributor to the development of degenerative joint disease--osteoarthritis--in performance horses.

After the initial impact phase comes the loading phase, when the leg accepts the horse's weight as compounded by the amount of thrust. The push-off or unloading phase follows. As the term suggests, this is when the leg pushes off the ground, elevating the horse, to maintain forward momentum. Tendons, ligaments and muscles experience the most strain during the loading and unloading phases. Toward the end of the unloading phase, the heels of the hoof rotate around the toe in the breakover.

The Physical Properties of Surfaces
The perfect formula for footing considers the biomechanics of a horse's step as well as the physical properties that influence performance and soundness: impact resistance, shear resistance and friction. Impact resistance indicates the density of compaction--the hardness--and the amount of concussion it causes. A hard surface, such as concrete or sun-baked clay, has a high impact resistance because it absorbs little, if any, of the impact energy. Consequently, the impact shock wave of the loading phase of a step must be absorbed almost entirely by the loaded leg. Therefore, high impact resistance is associated with large concussion.

Horses working on such surfaces tend to move conservatively in order to avoid excessive shock to their limbs. Under these conditions riders find that their normally free-moving horses have become short strided and stiff--often stumbling unaccountably--as they struggle to protect themselves against the unfriendly footing. This is what occurred in the late-summer show in the Midwest where the warm-up rings sat on a dry, sun-baked surface. Over time, horses working on hard surfaces are likely to develop bone and joint problems, especially degenerative joint disease, a frequent reason for dressage horses' premature retirement.

At the other end of the scale, deep wood shavings create a surface that has low impact resistance--which means that it absorbs the energy of the footfall. This is ideal for reducing concussion on legs, but it is very poor for preserving energy. Normally, a horse's leg stores some elastic energy in the ligaments and tendons during loading that is released to bounce the leg off the ground during unloading. To imagine what it is like for your horse to work on deep wood shavings, think of running on a track covered in pillows. A low-impact surface absorbs so much energy that your--or your horse's--muscles work much harder to provide sufficient propulsion. It has the effect of transforming a bouncy basketball into a medicine ball, and when this happens, there is a premature onset of fatigue.

The indicators of fatigue--raised heart rate, increased respiration, labored movement, inexplicable profusion of sweat-- need to be seriously regarded. To do otherwise is to flirt with strained muscles, tendons and ligaments. Suspensories,check ligaments, stiffles and backs are put at risk, and the potential for tying-up is increased.

Shear resistance describes the resistance of the surface to penetration by the toe of the hoof during the push-off phase of a stride. Ideally, the toe should be able to penetrate the surface in the terminal part of the push-off. It is at this time that the navicular region experiences the highest forces. The higher the density of compaction of the footing, the higher is the shear resistance--factors that explain why horses with navicular disease cannot perform well on hard footing. However, when the footing can be deformed by the toe during push- off, the force on the navicular bone is relieved because the hoof angle changes.

On a loose surface, such as deep, dry sand or shavings, the sheer resistance is low so the toe penetrates easily, but because the footing continues to yield during the critical push-off phase, it provides no support to the foot. Consequently, the soft tissue structures of the horse's legs must work harder to produce the necessary propulsion. Low shear resistance--a condition referred to on racetracks as a "cuppy track" --not only leads to fatigue, but because of the instability invites excessive lateral movement in the joints and thus increases the possibility of sprains--a condition exacerbated by fatigue.

Friction between the hoof and the ground determines the amount of resistance there is sliding over the surface. When the hoof makes impact with the ground, it is traveling forward. (The forward velocity is higher in the front hooves than in the hind hooves.) High friction stops the foot abruptly (it's like trying to waltz in sneakers) and low friction allows the foot to slide uncontrollably (like waltzing on rollerblades). Ideally, the hoof needs to be able to slide, but not to the extent that it cannot be controlled. With a high coefficient of friction, the impact of shock waves increases dramatically.

Either too much or too little friction reduces your horse's confidence in the surface and causes him to step shorter, keeping his feet low to the ground. In a word, he shuffles, losing impulsion altogether. It often takes a horse a while to regain his trust in his footing, so even if the footing in the showring is inviting, when you have to warm-up on slippery grass or trappy mud, your horse may go through an entire test before he feels secure enough to "loosen up." Too much time spent riding on high or low friction surfaces risks making long-term changes in your horse's posture and locomotion.

The Footing Formula

Ideally, an arena surface is somewhat deformable to absorb impact energy, yet sufficiently resilient to give the horse more spring. It allows him to move so that his hooves slide gently into the loading phase; it provides penetration during breakover as well as stability during push-off. In 1995, Klaus Fraessdorf won the USDF Footing Award for the footing in his main ring at the Clarcona Horseman's Park, and it does conform well to the criteria described above.

Fraessdorfs ring is a mixture of screened limestone (30 percent) and shredded--pea size--car tires (70 percent). The surface, which is three to four inches deep, allows a one-and-a-half-inch indentation by the horse. It lays on an extremely hard bed of limestone that has been compacted to the density of a highway bed. It is a crowned ring and, because of the sandy Florida soil, needs no other drainage system. This is a well-planned arena that uses a hard, underlying surface for stability and a precise combination of loose limerock and rubber to provide for optimal impact resistance as well as sheer resistance. Michael Poulin has said the ring is the best he's ridden, and that means he can count on his horses moving freely forward with confidence throughout the test.

Tempel Farms, on whose rings the Champion Young Rider has been determined for over a decade, enlisted the assistance of internationally renowned footing expert, Heraann Duckek, to mastermind the engineering of their arenas. The surface of the main competition arena is made up of an equal mixture of#2 sand (baseball diamond sand) and bagged pine shavings to a total depth of no more than two inches. The ring sits on a base of four to five inches of screened limestone which, like the Florida ring, has been compacted to a density comparable to concrete. The limestone was laid on hard clay that was carefully left undisturbed during the process of removing the rich Illinois topsoil in preparation for building the arena.

Unlike the Orlando ring, the one at Tempel Farms is not crowned but sits dead level. Interestingly, when the plane of the main competition ring was recently checked, it still was completely level even after eight years of competitions. Swales around the ring protect it from excessive downpours while a less-than-yearly addition of several hundred pounds of calcium chloride (300 to 500 pounds) helps to maintain the moisture at an optimal level. Roberta Williams recalls one competitor, who, tongue-in-cheek, complained about the footing, saying that it made his mare "too happy"--she had never had the experience of such perfect footing and was doing flying changes whenever she had the chance.

In Oregon, western Washington and British Columbia, ring makers use a tanbark indigenous to the area. It is heavier than shavings, so that on impact it condenses to provide stability in the loading and breakover phases of the step while increasing the energy in the unloading phase. The character of the bark and natural soil is such that these rings also require no drainage other than an engineered crowning of the ring.

Virginia and Maryland showrings use crushed rock or limestone, often mixed with sand--to help keep the rock from compacting to a cement-like density--and sometimes add pea-size wood chips or rubber for buoyancy. The absorbency of the stone precludes the necessity to add drainage as the rings remain stable even under standing water.

Clearly, the best footing is going to give you the best opportunity to make the best out of your horse. The question is "what is the best footing?" More specifically, what is the best footing in your area? Guidelines can be found in the USDF booklet, Underfoot, which currently is being updated by George Williams of Tempel Farms. And, of course, talking to experts in the field, especially those who are familiar with your area, its topography and weather, is the soundest way to go.

But what should you do when you arrive at a show with less-than-perfect footing? A lot depends on your creativity and good sense. Several years ago at a show in the mid-Atlantic region, a show manager had four inches of new sand added to his showring on the Friday preceding the competition. One top competitor whose horse had not been conditioned for such footing did not use good sense, was a "good egg" and competed, only to permanently compromise his horse's soundness. It would have been less costly to forfeit his entry fees.

On the other hand, when it was discovered that the footing in the warm-up of a prestigious East Coast show was hard enough to cause bruising, seasoned competitors got creative. They rose at dawn and used the outer perimeters of the groomed-to-perfection showrings for schooling. Then, for their tests--later in the day--they focused on limbering their horses up at walk and did very minimal concussive work, only enough to ensure their horses were on the aids. The seconds before entering the ring were used for short extensions. These riders' horses entered the ring supple and ready, unlike the competitors who had warmed up on the hard footing in the warm-up arena.

When the showring has obviously deteriorated, you can, to some extent, make adjustments in your tests. For instance, if there is a hole at X, most judges prefer to see a clean halt than one where you appear to be on water skis looking for a safe landing. On the other hand, no judge can score anything other than what he or she sees: If the ground is hard and your horse is stepping short, the judge is compelled to score a short-strided horse rather than what he thinks the horse could show under different conditions. Interestingly enough, though, most judges can remember situations when conditions were less than ideal, with many horses floundering in the ring, and yet the ones truly on the aids and working in balance managed to show well and without any missteps. So even when there's poor footing at a show, the best approach is to be confident that you can rely on the solid training you've done at home.

That said, although the perfect footing is difficult--seemingly impossible--to attain, the importance of working on good footing on a daily basis cannot be overemphasized. One or two training sessions or competitions on less-than-ideal footing are generally less detrimental to your horse than daily pounding on hard, slippery or "sucky" footing; nevertheless, such footing, even in short duration, may be sufficient to aggravate an injury or cause your horse to lose confidence. At shows, use common sense; at home, invest in securing your horse's footfalls. ~

Hilary Clayton, BVMS, PhD, MRCVS, is the McPhail Dressage Chair in Equine Sports Medicine at Michigan State University.