The response of some mammalian supporting tissues and structures to mechanical loading

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Every time a horse's hoof hits the ground it experiences shock from the impact then force as the weight of the body is borne by the leg. The impact distributes energy to hoof wall and the soft-tissues and bones it contains, and the force induces stress and strain in them.  Different regions and tissues of the hoof experience varying amounts of stress and strain, and the distribution of energy, stress and strain in a single footfall is called the mechanical behaviour of the hoof.  The hoof is like also bone and muscle in that it can respond over time to changes in the amount of impact and force it experiences per day.  This proposal is to support several experiments each exploring a different possible way that the hoof might respond to changes in impact and force over time.  The first is to test how the laminar junction - the strong layer supporting the hoof wall on the bone inside it - remodels under varying stresses and strains.  We'll use computer modelling of real hooves to calculate the stress and strain in the laminar junction of each, then compare the stress patterns with patterns in the structure of the laminar junction.   The laminar junction also absorbs much of the energy of impact.  So the second test is to compare the laminar junction's  ability to absorb impact among hooves that have worked on surfaces that change the amount of energy needing to be absorbed.   The final test is to culture cells that form the hoof as they grow to examine their responses to varying levels of stress, by determining the effects on their rates of growth, and expression of certain genes.This work will lead to an understanding of how the hoof has adapted its 'fingernail' to become part of the weightbearing musculoskeletal system - this is a question of general interest to biologists.  It will also help ascertain how the hooves of individual horses adapt to changes in loadbearing requirements during their lifetimes - this is of biological interest, and also has implications for hoof care and the prevention of lameness in riding horses.