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Research: Assessing Asymmetry in Event Horses


 by Mel Betts, McTimoney Practitioner


Successful event horses need to be some of the most adaptable and physically fit of all equine disciplines to compete in the three demanding phases of dressage, cross country and show jumping.  The sport places extreme demands on the musculoskeletal system through working at speed on variable gradients and terrain. Trauma is also an issue.  One in three horses that fall injure themselves, while one in 100 falls result in horse fatality, (Murray et al, 2006). 


Further, the risk of injury is not limited to competition alone.  Up to 21% horses in one study failed to reach their targeted competition due to an injury sustained during training (Singer et al, 2006).  In event horses the hind limbs, particularly the stifle area, are most commonly injured, (Dyson, 1994).  Due to the physically demanding nature of their work and the high risk of trauma, event horses are be particularly vulnerable to the development of misalignments in the vertebral column and pelvis which could affect performance.


Alignment through a symmetrical pelvic rotation has been linked to performance.  It has for example, been described as one of the hallmarks of good gait (Gomez Alvarezet al, 2008).  Holmstrom et al (1994) also indicates the pelvis, hock and hind fetlock joins are the most important parts of the system for storage of elastic strain energy. 


Further, a lack of pelvic symmetry in the equine athlete has been linked to poor or lower performance in a number of studies (Dalin 1985, Boyd 2008).  Dalin (1985), looked at asymmetry in relation to competitive success and found that affected horses had significantly lower total earnings, lower number of races and slower race speeds.  If left unresolved, it has also been suggested that pelvic asymmetry, as a result of compensatory gait patterns, may produce subsequent remodelling of the pelvis, (Haussler et al, 2009).  


The aim of McTimoney manipulation is to restore the normal range of motion of the joints through the release of muscle spasm and therefore the realignment of symmetry.  We know Human marathon runners use complimentary therapies, including chiropractic techniques, with the aim of achieving symmetry to prevent injury and to enhance general well-being.  However, the benefit of such therapy to horses is more difficult to prove, as published data on the effectiveness of alternative therapies is limited. 


One study found chiropractic treatments in horses reduced pain, (Haussler et al 2003).  Sullivan et al, (2008) also found that chiropractic treatment increased spinal mechanical noiceptive thresholds in horses.  Further unpublished studies have attempted to make links between alternative therapies and improved performance.  Trott, (2008), concluded that improvements in stride parameters were seen following a single McTimoney treatment.  Boyd (2000), found asymmetric horses on a racing yard which undertook McTimoney manipulation, had more starts and longer racing careers than the asymmetric horses on the control yard. 


The prevalence of pelvic asymmetry in the general horse population is also difficult to assess.  This is mainly due to the differences in measurement techniques and the different breed types of horses used in the limited available studies on pelvic asymmetry.  Dalin (1985) found that 8% of standard bred trotters had pelvic asymmetry while, Haussler et al (1999), using more precise measurements post-mortem, cited 94% of Thoroughbred (TB) racehorses studied had a tuber sacrale asymmetry. 


My own study entitled: The Immediate Effect of McTimoney Treatment on the Pelvic Asymmetry Found in Eventers,  aimed to determine the general prevalence of pelvic asymmetry in eventers and to assess the immediate effect of a single McTimoney treatment on any asymmetry found.


A cohort of horses (N=20) from one of the largest event yards in the UK were used in this study.   The sample was divided into a treatment (N=9) and control group (N=11) to assess the immediate effect of a single McTimoney treatment on the degree of pelvic asymmetry found.   Records of height, age, gender, eventing level, hind limb bone lengths and degree of pelvic rotation and tilt prior and post intervention were recorded. 


The results of this study indicate that the majority of eventers exhibit pelvic asymmetry.   The study showed that 85% (N=17) of the sample had a pelvic rotation and 85% (N=17) exhibited a pelvic tilt.  However, this study did not find a relationship between height, age, gender or eventing level and the degree of pelvic asymmetry in eventers.


The study did show that following a single McTimoney treatment, the treatment group exhibited less pelvic asymmetry post intervention than the control group in relation to both pelvic rotation and tilt.  However, due to limitations with the number of horses within the study and other variables, these findings were not statistically significant.  




This study looked at the effects of a single McTimoney treatment on a cohort of eventers.  However, a single treatment may not have been sufficient to alter long standing patterns of compensation in some individual animals and therefore it was concluded that future research could investigate any subsequent improvements following a prescribed course of McTimoney therapy over time. 


It was also concluded that future studies into the pelvic asymmetry of eventers should attempt to use larger sample sizes and control more of the variables to create more matched sample data.   Future research should also take into consideration previous complementary therapies that the sample may have been given previously, so the effect of McTimoney treatment alone, could be more accurately assessed.







Betts, M (2011), The Immediate Effect of McTimoney Treatment on the Pelvic Asymmetry Found in Eventers. McTimoney Thesis, unpublished data.



Boyd, F. (2008), Comparison of Pelvic Asymmetry and Racing Performance as a Measure of McTimoney Animal Manipulation in National Hunt Racehorses.   McTimoney Thesis, unpublished data.


Dalin, G., Magnusson, L.E. and Thafvelin, B.C, (1985), Retrospective study of hindquarter asymmetry in Standard bred Trotters and its correlation with  performance.    Equine Veterinary Journal 17, 292-296.


Dyson, S, (1994), Stifle Trauma in the Event Horse, Equine Veterinary Education, 6 (5) 234-240


Gomez Alvarez, C. B., L'Ami, J. J., Moffatt, D., Back, W. and van Weeren, P. R. (2008), Effect of chiropractic manipulations on the kinematics of back and limbs in horses with clinically diagnosed problems. Equine Veterinary Journal 40, 153-159.


Haussler, K. K., McGilvray, K. C., Ayturk, U, M., Puttlitz, C. M., Hill, A. E. and McIlwraith, C. W,  (2009), Deformation of the equine pelvis in response to in vitro 3D sacroiliac joint loading.  Equine Veterinary Journal. J. 41, 207-212.


Haussler, K, (2009), Review of Manual Therapy Techniques in Equine Practice.  Journal of Equine Veterinary Science, Vol 29, No 12.


Haussler, K.K. and Erb, H.N. (2003)  Pressure algometry: Objective assessment of back pain and effects of chiropractic treatment.  Proc. Am. Ass. Equine Practitioners.  49, 66-70.


Haussler, K. K., Stover, S.M. and Willits, N.H. (1999), Pathology of the lumbosacral spine and pelvis in Thoroughbred racehorse,  Am. J. Vet. Res. 60, 143-153


Holmstrom, I., Fredricson, Drevemo, S. (1994) Biokinematic Differences Between Riding Horses Judged as Good and Poor at the Trot.  Equine Veterinary Journal Supplement 17 P51-56.