The study, titled ‘Physics of animal health: On the mechanobiology of hoof growth and form’, represents the fruit of a collaboration between researchers in equine medicine, maths, physics and stem cell biology. It was conducted by the School of Veterinary Medicine and Science at University of Nottingham in collaboration with the Waltham Centre for Pet Nutrition and the Royal Veterinary College.
Lead author Dr Cyril Rauch said: "With new scientific inputs from physics, mathematics and biology, this study provides an entirely new paradigm regarding hard growing tissues such as the horse hoof, which can be applied across cattle, sheep and other species, to unify a set of apparently disparate conditions and clarify the roles of physics and/or biology."
Using hooves from horses euthanased for non-research purposes, the study revealed how it is possible for the hoof growth rate to be greater than the potential proliferation rate of epithelial cells. It also explained how the synthesis of the hoof capsule starts from the coronet and that the soft papillae undergo gradual transition through three interpapillary regions into hard keratinised tissue.
Mathematics, physics and cell biology were then used in the study to explain and describe how the dorsal hoof wall can grow in a curved manner rather than the usual straight manner as a result of faster growth from the coronary band at the quarters compared to the toe region.
Evaluation of the feet from live underweight and obese subjects (assessed using Body Condition Scoring) allowed the influence of body weight on the balances of the stresses affecting hoof growth to be evaluated. The results suggest that being proportionally heavier may promote straighter hoof growth and that being too lean may precipitate poor hoof growth and the development of a hoof with a dorsal curved shape.
The study also showed that a high concentration of insulin stimulated equine progenitor keratinocytes (the outermost layer of cells on the hoof wall) to grow in culture. If this also happens chronically within the live animal, it is possible that it could affect the growth stresses within the hoof and so promote a dorsal curved hoof shape.
Co-author Nicola Menzies-Gow said: "These results taken together can explain how the hoof grows and how it is possible for it to develop a dorsal curvature. However, it should be acknowledged that this does not take into account the genetic or metabolic influences on hoof growth nor the role of hoof trimming and shoeing in maintaining a mechanically healthy hoof. It is appreciated that the underlying biology of hoof growth remains an essential factor for hoof pathologies."
Dr Cyril Rauch continued: “Given that the hoof is a weight bearing element it is essential to untangle the biology from the physics in this system; only then can meaningful biological and/or physical causes be prescribed for particular hoof shape. Removing the cause(s) when physically or biologically possible is essential to resolve hoof conditions."
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