Anatomical Symmetry: Where does normality lie?

Activity: Talk or presentation typesConference Keynote speech


Within a range of species, including humans, structural asymmetry has been proposed as an indicator of genetic quality through association with factors including disease resistance, mate choice and performance potential. Whilst research into equine biomechanical asymmetries is a rapidly expanding field, there is comparatively little research regarding equine structural asymmetries. The overarching aims of the research being presented includes an attempt to establish the existence, direction and magnitude of distal limb asymmetries within both competitive and non-competitive equine populations. Furthermore, the findings have provided a preliminary picture as to whether a ‘normal’ level of directional asymmetry exists within the distal limb and hoof of the horse, irrespective of competitive standing.
Previously published literature postulated associations between equine bilateral trait asymmetries and either the locomotor directionality of the competitive discipline, or indeed their associated selective breeding strategies. As similar patterns of distal limb asymmetry have been confirmed in event horses and leisure horses, the discipline demand theory of asymmetry development is refuted. The comparative patterns of asymmetry across differing population implicates a species level presence of asymmetry, as opposed to a breed, or discipline level association. However, the findings indicate that whilst bilateral asymmetry is present at a species level, horses with a proven superior athletic ability present with a greater affinity for symmetry. The asymmetries investigated are not of a magnitude likely to have a significant negative, short term effect on biomechanics. Instead, they are theorised to reflect internal disturbances; of what, and at what structural level, is yet to be determined.
Furthermore, dynamic form of the equine hoof does not compensate for distal limb asymmetries; Instead, conformation of the hoof is impacted by the loading imbalance caused by the asymmetries. To compound this further, asymmetries of the hoof increase within an increase in the size of the horse, suggesting larger horses are subject to both greater, and more imbalanced loading forces; an area of significant concern for both performance and welfare.
Period29 Mar 2023
Event titleBSAS Conference 2023 : Animal science: Delivering for all our needs
Event typeConference
LocationBirmingham, United KingdomShow on map
Degree of RecognitionNational


  • equine
  • asymmetry