title: An investigation into the use of hoof balance metrics to test the reliability of a commonly used foot trimming protocol and their association with biomechanics and pathologies of the equine digit.
Creators: name: Caldwell, MN
Publisher: name: University of Liverpool Repository
Year: 2017

description: The equine foot has a specific conformation (shape) that provides maximum biomechanical efficiency. Biomechanical efficiency allows the foot to withstand, accept, absorb, dissipate and transmit loading weight bearing forces in a manner that offers the greatest protection to the horse. This principle implies that there is some combination of foot size, foot shape, wall length and angles that make the foot an ideal shock absorbing, weight-bearing structure. It is the proper combination of these variables are said to constitute what has been described as the properly balanced foot. However, there are currently several conflicting hoof balance reference systems commonly utilised and what constitutes ideal balance has been the subject of great debate for many years. One goal of the research was to investigate the principle of equal geometric proportions and dependentcy on factors such as foot-type and environmental conditions. By utilising a standardised trimming protocol and a hoof mapping system to collect measurement data based on proportionality of the bearing border length the purpose of this study was, partly, to verify whether a commonly used theory of hoof balance, firstly described by Duckett, is achieved. Secondly to determine whether geometric proportions are equivalent following trimming, thereby achieving hoof balance. Analysis suggested Currently accepted interpretations of static hoof balance including the achievement of an aligned phalangeal axis and a ground bearing border bisected by CoR are likely to be outmoded. This provides support to the hypothesis that feet should be managed on an individual basis rather than a “one-size fits-all” approach commonly applied and that implementing a prescriptive model may even be counter-productive to the functional integrity of the hoof. Farriery technique have been shown to influence skeletal alignment within the foot. Standardised trimming and shoeing protocols were used to test the hypothesis that shoeing, over an extended period of time, would result in significant differences in static hoof balance proportions. Results showed that horses managed unshod had greater ability to manipulate bearing border length, re-align the heel angle and allow palmar heel migration than shod horses. Furthermore, proportional hoof balance measures were able to be altered in unshod feet and that equivalence of the proportional hoof measures were not present in either cohort (unshod/shod). The significant differences in hoof measures present in shod feet ie; flattening of the sole, heel contraction, reduction in dorsal hoof wall and heel angulation and dorsal migration of dorsal hoof wall and heel seemed likely to reflect the effect of the shoe over an extended period. The application of a standard steel horseshoe appeared to influence hoof shape and is likely to both affect and be affected by mechanical forces acting on the foot. The affect of hoof shape and the mechanical forces experienced by the foot itself following the application of the standardised trimming protocol and the application of a shoe were investigated. Results highlighted significant post-shoeing statistical differences in all dynamic measurements between shod and unshod feet. Specifically post-shoeing reductions in peak pressure and the contact area resulting in differences in peak force and peak force time were noted. These results partially support the propersition of a difference in mechanical behavior of the foot under load and may reflect the differences witnessed in feet under different management regimes. Biomechanical analyses of this kind enable improved understanding of hoof function, and a rational, objective basis for comparing the efficacy of different therapeutic strategies designed to address hoof dysfunction and pathology. There is considerable anecdotal information that poor foot conformation and balance are associated with an increased risk of foot-related lameness but foot imbalance may also result from lameness as an adaptation to chronic pain. Utilising MRI findings from a group of horses referred for lameness investigation bionominal logistic regression was used to test the hypothesis of risk of lameness associated with hoof measurement proportions. There is evidence to suggest a strong correlation between hoof conformation and the biomechanical inference on anatomical structures and foot-related pathologies. Variation in key hoof measurement proportions resulted in significant differences in risk factors of specific common foot pathologies ie; navicular disease and degenerative joint disease of the distal interphalangeal joint. It has been argued that the form of the solar arch was indicative the pathologies. Results from the current study appear to support his hypothesis by linking hoof morphology to the incidence of disease. Whilst the author recognises that hoof shape is influenced by any number of other factors, proportional values along the solar axis may well prove to be a good model for biomechanical efficiency either by trimming alone or form the basis of a more biomechanically sympathetic standardised shoeing model.