24/09/2024
Jak může low heel/high heel ovlivnit pasování sedla 💡
This is the second post in our equine asymmetry series.
If you missed the first post, scroll back to "Laterality & Asymmetry" to get up to speed.
We concluded that laterality and asymmetry are natural in horses. While more ambidextrous horses tend to exhibit less asymmetry and perform better, most horses display a notable degree of laterality.
Horses that are unbalanced or asymmetrical place excessive strain on one side of their bodies, making them more susceptible to injuries. Given that musculoskeletal injuries are a leading cause of early retirement in horses across all disciplines, this is an issue worth examining closely.
Most of us have heard the famous saying “No hoof, no horse,” and it holds true in the context of asymmetry, as your horse's feet play a crucial role here too.
Research confirms that a substantial percentage of horses have uneven feet, with many displaying a larger left hoof capsule compared to the right.
Low Heel/High Heel Syndrome is characterized by asymmetrical heel heights, most commonly observed in the front feet. When asymmetry occurs in the body or limbs, compensatory mechanisms arise, leading to postural changes. These shifts ultimately affect locomotion, and when movement becomes asymmetrical, both performance and soundness can suffer.
The problem with asymmetry and Low Heel High Heel Syndrome is that there is a significant genetic component that has been largely overlooked in modern breeding practices. This has resulted in many horses whose bodies’ tolerance for asymmetry has been exceeded.
In the wild, excessive functional asymmetry can compromise a horse's ability to escape predators, ultimately influencing survival and reproduction. In contrast, our domestic environment does not have the same natural checks and balances.
Instead, we often inadvertently introduce horses into the gene pool whose asymmetries surpass the threshold of balance tolerance.
This can perpetuate genetic traits that predispose horses to asymmetry. But that’s a whole other can of worms...
What Happens with the Lower Heel?
Postural deviations in the lower-heeled limb create significant changes in joint angles, particularly at the pastern, fetlock, elbow, and shoulder joints. Compared to the higher-heeled limb, the angles in the low-heeled limb open up, leading to a more vertical alignment. The pastern and fetlock joints become more extended and may risk subluxation, while the elbow angle also becomes more open.
As the shoulder joint adjusts, the “point” of the shoulder shifts backward, resulting in a more vertical scapula and a noticeable bulge in the shoulder on the lower-heeled side.
This bulging shoulder may appear higher than its counterpart, while the higher-heeled shoulder often shows a pronounced slope. Although not anatomically shorter, the limb is functionally shorter.
So, let’s connect the dots...
Hypothetically, if a horse has a motor laterality that causes right-side dominance, they will stand with the left leg forward during grazing, using the right (dominant) leg to support their body weight. Because the muscles on the dominant side are typically shortened, leading to natural flexion, the mane will likely fall to the right, the more dominant side.
The right hoof will be the higher-heeled foot, whereas the left foot will be lower-heeled.
Due to the postural changes explained above, the left shoulder shifts backward, resulting in a more vertical scapula that appears higher than the right side and presents a noticeable bulge. Meanwhile, the right shoulder remains further forward, exhibiting a more pronounced slope.
This asymmetry in the horse’s hooves results in postural deviations that significantly affect shoulder symmetry and saddle fit...
..which we will get into tomorrow!
Primary Sources:
Van Heel, M. C. V., van Dierendonck, M. C., & Kroekenstoel, A. M. (2010). Lateralised motor behaviour leads to increased unevenness in front feet and asymmetry in athletic performance in young mature Warmblood horses. Equine Veterinary Journal, 42(5), 444-450.
Kuhnke, S. (2020). Horse's laterality: methods of determination, genetic aspects, interaction with human handedness and the influence on horse-rider communication, horse's muscle status, sport success... [Thesis]. Justus-Liebig-Universität Gießen.
Ridgway, K. J. (2003). Low Heel/High Heel Syndrome: Unrecognized Problems. Presented at ‘A BRIDGE TO THE FUTURE’ Veterinary Conference, August 10, 2003.
