In horses, the mechanical properties of the hoof wall are, to a large extent, a function of its structural arrangement. Grossly defined parts of the hoof protect underlying structures of the foot and initiate dissipation of concussive forces on impact when the hoof strikes the ground.1 In response to the imposed stresses, the hoof undergoes elastic deformation. During weight bearing, the dorsal hoof wall rotates caudodistally while the quarters and heels flare abaxially.2 These deformations of the whole hoof capsule cause regional variations in the stress and strain of the material of the wall, which can be recorded as principal strains.
The combination of the horse's weight, high-speed gait patterns, and contact with uneven surfaces augment the chance of developing high localized stress concentrations within the hoof.3 However, the equine hoof wall has a unique architectural design that enables it to withstand the forces generated during weight bearing and through the impact of the hoof hitting the ground. The hoof is a dynamic structure able to respond to changes in its environment, such as changes in loading.4–9 Various factors influence its biomechanics, including but not limited to shape,10–16 shoeing,17–22 substrate,23–26 breed,27 speed,28 and rider.29 Although it has been shown that the equine limb as a whole can adapt to the stresses imposed, much of this attention has been paid to the third metacarpal bone and associated tendons and ligaments,30–33 whereas some of the hoof's responses to exercise have not been documented. There is empirical evidence that the hoof may respond to changes in its environment,6 but to the authors' knowledge, this has not been explored experimentally.
Biological responses of the hoof to loading under conditions of controlled exercise have not been quantified in experimental conditions. The purpose of the study reported here was to quantify changes in hoof wall strain distribution associated with exercise and time in Standardbreds.
Lateral quarter of the hoof wall
Medial quarter of the hoof wall
Midstance maximal principal strain
Midstance minimal principal strain
Peak minimal principal strain
Professional Farrier Supply Inc, Orangeville, ON, Canada.
N32-FA-2–120–11, Showa Measuring Instruments Co Ltd, Tokyo, Japan.
Loctite 411, Loctite Canada Inc, Mississauga, ON, Canada.
Vetrap, 3M Animal Care Product, Saint Paul, Minn.
Logbook/300, Iotech Inc, Cleveland, Ohio.
Gauss Data Analysis Software, Aptech Industries, Seattle, Wash.
PROC MIXED, SAS, version 9.1.3, SAS Institute Inc, Cary, NC.
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