What Veterinarians in Sport Horse Practice Should Know About Farriery
Fernando J. Marqués, DVM, Diplomate ACVIM, Diplomate ACVSMR
In sports, it is all about performance keeping the athlete in the best fitness level possible, while preventing the occurrence of training-related injuries. It is well known how common soft tissue and bone lesions are in sport horses, regardless of the discipline in which they are involved. Many factors play a role in sports-related injuries but having a horse with good foot structures and balance is of paramount importance for preventing tissue damage, lameness, and poor performance. Prevention is key, and good farriery is one of the most important practices that veterinarians need to keep in mind. Farriers and veterinarians must work in sync which will yield a good relationship and benefit the horse.
Understanding fundamental farriery principles such as assessing conformation, biomechanics, center of rotation, and hoof proportions is of utmost importance. This short commentary is not meant to go into depth about all the physics involved in the different phases of the stride, foot/limb anatomy, and biomechanics, which can all be found in many textbooks and scientific papers, but a brief discussion of some key practical points.
During the stance phase of the stride, based on the Newton's third law of motion, whenever the foot and the ground interact, they exert forces upon each other. This external impact force exerted by the ground to the foot is called ‘ground reaction force’ (GRF), the magnitude of the force is determined by speed of movement, weight of the horse, and the characteristics of the footing surface. Horses train on different ground surfaces, and the interaction between the foot and the ground surface have a dynamic impact on the adaptation of the muscles, bones, tendons, and ligaments to the demands of exercise, therefore, this interaction plays a major role in the risk of injury. Furthermore, any alteration in footing and/or on hoof structures/ balance by virtue of farriery, has a huge influence on injury risk and lameness occurrence. It is worth mentioning, that the foot adapts over time in relation to the forces applied to it. This takes place by altering its growth rate and/or foot shape, in addition to its structural characteristics. Inappropriate trimming and shoeing, either in the short term or the long term, will ultimately lead to tissue damage, uneven gaits, poor motion patterns, lameness, and poor performance.
Both latero-medial and dorso-palmar hoof balance need to be considered. A practical method of ensuring an appropriate dorso-palmar hoof balance is by observing the distal limb of the horse from the side (latero-medial view), then using both thumbs, palpate the dorsal and palmar borders of the second phalanx in a distal direction until reaching the coronary band. A point equidistant from both thumbs at the level of the coronary band can be established (Figure A). From that point on the coronary band, one should imagine a straight line perpendicular to the ground, which should divide the hoof into approximately two halves, one half dorsal to the line and the other half palmar to the line (Figure A). That line perpendicular to the ground will also coincide with the widest point of the foot when looking at it from the solar aspect (from the bottom). The widest point of the foot is generally 1.5 to 2 cm palmar to the true frog apex, and more importantly, the center of rotation of the distal phalanx is approximately one centimeter palmar to the widest point of the hoof (Figure B). Following these simple general measurements and proportions will not only allow the clinician to evaluate the foot but also to apply trimming and shoeing to a sport horses with a balanced dorso-palmar distribution of forces acting on the foot. In conclusion, it should be noted that when both the trimming and shoeing are done properly, “the shoe is seen under the horse and not in front of the horse”.
Aside from all the technical considerations, one of the most important things I have learnt throughout my career in academia and private equine practice is working with a team approach. Many challenging lameness cases will likely have a great outcome if there is a real and open-minded dialogue between farrier and veterinarian. It is not all about the farrier, or the veterinarian, but it is about the teamwork. Having a team approach between farrier and veterinarian gives the best chance for a horse to maintain an excellent performance level and / or regain that level faster when recovering from a lesion. Work ethics, modesty, respect, fluent and honest dialogue, and willingness to learn from each other are desired characteristics for a professional interaction between farrier and veterinarian.