I recently visited the New Forest and the foot balance (or lack of) on these wild (ish) ponies reminded me of a study that I had heard about and it got me thinking…
The Study
In 2006 a group of researchers from the Netherlands published a study investigating the development of uneven feet as a consequence of lateral grazing behaviour induced by conformational traits. This is a mouthful that I will attempt to unpick for you whilst providing my reasoning as to why this research is important to you, the horse owner.
The study demonstrated that a very significant number (46%) of the study population (24 foals) developed laterality (dominance within one side of the body) when grazing. This means that one foreleg was predominantly forwards whilst the other was backwards, in the same way that we become left or right handed. The remaining percentage also developed laterality, just to a degree considered insignificant.
Those that had relatively long legs and small heads developed greater laterality as they had to spread their legs further in order to reach the ground.
The above image was sent to me by a client after reading the abbreviated version of this discussion on Instagram. She has had trouble with asymmetry and lameness in this horse who is now a mature horse. The study in question found that longer legs and smaller heads resulted in a greater degree of asymmetry within the feet - the forwards foot becoming long and flat and the backwards foot becoming upright and ‘boxy’. Interestingly the foal in the above image seems to have both of these traits, and also a short neck.
Uneven feet essentially lead to uneven loading patterns and it is widely assumed that this causes a predisposition to injury at maturity. The researchers involved in this study explain that most of today’s sports horses are required to perform on the left and right reins and straight (symmetrically). Any form of laterality (limb preference) could influence their ability to do so - and their ability to remain sound. Is your horse 'better on one rein'?
So how do we prevent uneven hooves?
Regular foot trimming and feeding from higher than ground level, right?
Unfortunately the answer is not so simple. The study found that regular trimming will not prevent the development of unevenness. Additionally, housing foals indoors in order to control the height from which they are feeding is detrimental to the development of other musculoskeletal tissues.
We are now armed with scientific evidence that our horses often suffer from a degree of laterality which might negatively affect performance and soundness, but what can we do to reduce the effects? To answer this question we need to understand the principles of training.
Training Methods
Common training techniques such as progressive loading ensure that tissues are stressed enough to elicit adaptation, without causing injury (Blanchard & Glasgow, 2014). Marcellin-Little, Levine & Taylor (2005) further explain that excessive frequency (the number of times an exercise or movement is performed), intensity (e.g. speed or distance) or duration may cause injury. Unfortunately ‘enough’ and ‘too much’ is subjective (based on personal feelings or opinions) as this varies between individuals due to intrinsic (e.g. age) and extrinsic (e.g. diet) factors. However, you may already know more on this subject than you realise.
Many unwritten rules exist in the horse world - we don’t jump every day of the week so as to not overload tendons and ligaments, when fittening we don’t gallop more than twice a week so as to avoid fatigue. As a coach and therapist I have observed that we have little understanding as to how often to strength train, or of what strength training involves. Is this because strength is hard to assess in horses? A human can tell you “I was able to lift 10kg more this week”, whereas in our horses the assessment of strength is difficult to quantify and distinguish from other factors. For example, “my horse carries me up the hill more easily than he used to” - this could be due to improved strength and/ or cardiovascular fitness. However, it is widely accepted that to improve strength in humans, strength training three times per week is sufficient.
Another important training consideration is ‘cross training’. This involves different types of exercise at different paces, over varying terrain (uphill/ downhill, rough ground/ flat ground, deep ground/ firm ground) and performing different movements that are relevant to the final goal (e.g., a specific competition discipline). This ensures that the tendons, ligaments, bones and joints are stressed in different ways so that they are able to cope with the varying demands of exercise.
So what is the point?
Think about the ridden horse, which exercise do all ridden horses perform regularly which requires the greatest degree of strength?
Carrying you!
If we know that strength training three times per week is sufficient to elicit and increase in strength in humans and that too much strength training can induce fatigue, are we asking our horses to carry us too often? If we link this back to our knowledge that our horses often suffer from a degree of laterality, it can be assumed that increasing the weight carried may increase the negative impact of laterality on performance and soundness. Many horses also work in the menage many times per week which requires lots of turning. Remember, these researchers mentioned that any degree of laterality affects the horses ability to work left and right as well as straight, possibly predisposing them to injury. In addition, lots of work on that lovely flat surface in the menage doesn’t particularly contribute to cross training or improved coordination which can predispose your horse to injury.
Take home message?
Everything in moderation
Consider reducing the weight your horse carries, or the frequency (number of days) which they carry weight
Consider the frequency (number of days), intensity (walking/ trotting/ cantering), and duration that your horse spends in the menage - working on constant turns
Cross train
Ensure that your horse is worked over varied terrain
Perform a variety of exercises such as long-reining, hacking, lunging
Hacking is a great way to reduce turning and to vary terrain
Long-reining is a great way to remove the rider without the constant turning required when lunging
Learn
Acquire a solid base knowledge and understanding of training methods and principles
Further reading:
Further reading on the effects of circling on forelimb kinetics (forces), movement symmetry and lameness;
Chateau, H., Camus, M., Holden-Douilly, L., Falala, S., Ravary, B., & Vergari, C. et al. (2013). Kinetics of the forelimb in horses circling on different ground surfaces at the trot. The Veterinary Journal, 198, e20-e26. doi: 10.1016/j.tvjl.2013.09.028
Pfau, T., Stubbs, N., Kaiser, L., Brown, L., & Clayton, H. (2012). Effect of trotting speed and circle radius on movement symmetry in horses during lunging on a soft surface. American Journal Of Veterinary Research, 73(12), 1890-1899. doi: 10.2460/ajvr.73.12.1890
Starke, S., Willems, E., May, S., & Pfau, T. (2012). Vertical head and trunk movement adaptations of sound horses trotting in a circle on a hard surface. The Veterinary Journal, 193(1), 73-80. doi: 10.1016/j.tvjl.2011.10.019
Thomsen, M., Sahl-Tjørnholm, C., Sørensen, H., & Tolver, A. (2014). Effect of Lungeing and Circle Size on Movement Symmetry in Sound Riding Horses. Equine Veterinary Journal, 46, 49-50. doi: 10.1111/evj.12267_151
Further reading on the principles of training;
Anemaet, W., & Hammerich, A. (2014). A Framework for Exercise Prescription. Topics In Geriatric Rehabilitation, 30(2), 79-101. doi: 10.1097/tgr.0000000000000011
Blanchard, S., & Glasgow, P. (2014). A theoretical model to describe progressions and regressions for exercise rehabilitation. Physical Therapy In Sport, 15(3), 131-135. doi: 10.1016/j.ptsp.2014.05.001
Marlin, D., & Nankervis, K. (2013). Equine Exercise Physiology. New York, NY: John Wiley & Sons.
McGowan, C., & Goff, L. (2016). Animal physiotherapy. Chichester: Wiley Blackwell.
References
Blanchard, S., & Glasgow, P. (2014). A theoretical model to describe progressions and regressions for exercise rehabilitation. Physical Therapy In Sport, 15(3), 131-135. doi: 10.1016/j.ptsp.2014.05.001
Brama, P.A., Tekoppele, J.M., Bank, R.A., Barneveld, A. and van Weeren, P.R. (2002) Biomechanical development of subchondral bone from birth until age eleven months and the influence of physical activity. Equine vet. J. 34, 134-149.
Goodship, A.E. and Birch, H.L. (2001) Exercise effects on the skeletal tissues. In: Equine Locomotion, Eds: W. Back and H.M. Clayton, W.B. Saunders, London. pp 227-250.
Heel, M., Koekenstoel, A., Dierendonck, M., Weeren, P., & Back, W. (2006). Uneven feet in a foal may develop as a consequence of lateral grazing behaviour induced by conformational traits. Equine Veterinary Journal, 38(7), 646-651. doi: 10.2746/042516406x159070
Loving, N. (2015). Managing the Club Foot. Retrieved from https://thehorse.com/117078/managing-the-club-foot/
Marcellin-Little, D., Levine, D., & Taylor, R. (2005). Rehabilitation and Conditioning of Sporting Dogs. Veterinary Clinics Of North America: Small Animal Practice, 35(6), 1427-1439. doi: 10.1016/j.cvsm.2005.08.002
Shutterstock. (2019). Foal Grazing in the Pasture, Stock Footage Video (100% Royalty-free) 11938703 | Retrieved from https://www.shutterstock.com/video/clip-11938703-foal-grazing-pasture-brown-filly-horse-springtime
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