Ask Your Veterinarian Presented By Equistro: How Much Does Yearling Conformation Matter On-Track?

by | 08.06.2018 | 3:53pm

Question: How would the conformation of my yearling affect his racing career?

Dr. Raul Bras: Obviously, this is a loaded question that we wouldn't be able to answer with a short description. Also, we must understand that evaluation of equine conformation is usually subjective and based upon experience or opinion. Conformation is the physical appearance of an animal due to the arrangement of muscle, bone and other body tissue. Good conformation is the overall blending of this traits and simply the relationship of form to function to form a successful athlete.

There is a belief among many people that defects in conformation predispose racehorses to poor performance and injury. The cause of racing injuries in the horse is considered to be multi-factoral with genetics, race surface, number of starts, age of the horse, pre-existing pathology, biomechanics (conformation) and trauma being implicated as potential etiologic agents. Horses with obvious conformation problems tend to bring lower prices at public auction.

Remember, every horse has some fault with regard to pedigree and conformation. The art or science of evaluating a horse is deciding which of those faults are less likely to adversely impact the horse's racing career. It is helpful to know something about the pedigree of the horse as it may relate to a particular horse's conformation. Some stallions pass similar conformational faults to their offspring, with some of the faults having little or no consequence with respect to their racing success.

The causes of conformational deviations are a matter of some debate, and genetics and external forces are the major factors considered. Presently, this complex situation is incompletely understood, but is seems clear that both biological and mechanicobiological influences must be considered. Over the years, various studies of conformation faults and racing performance have produced contradictory results.

Dr. Raul Bras

Conformation variations previously reported to be important in the occurrence of carpal fractures include; the morphology of the carpus, foot and lower limb, particularly long toes, low heels and long sloping pasterns (Barr 1994). Although not associated with fractures, the odds of effusion in the left carpus increased for 10 percent increase in the dorsal palmar hoof angle ratio (dorsal versus heel angle- more ‘under-run'), indicating the importance of correct dorsal palmar balance in the hoof. This supports anecdotal opinions, but may be inconsistent with a previous study that reported that horse with higher hoof angles presented fewer musculoskeletal problems (Kobluk et al 1990)(Mcllwraith). Toe angle has been shown to have an effect on the deep digital flexor tendon and extensor branches of the suspensory ligament. Deep digital flexor tendon strains decreased as toe angle increased from 55 to 78°. Further conformation abnormalities of the foot, especially foot imbalance, may predispose the development of pain associated with the distal interphalangeal joint.

A horse's hooves must be able to withstand a great deal of pressure. At full speed, a 500 kg Thoroughbred will place the equivalent of 100 times the force of gravity on each hoof with every stride, so it is essential that the foot be shaped properly to withstand this concussion and to dissipate the shock of impact. Consider the proportion, substance and size of the hoof. The underside of the hoof should have a round, slightly oval shape, with some depth. The Thoroughbred foot is often plagued with chronic problems, such as thin soles, weak walls, crushed heel tubules, bull-nosed or dished walls, negative palmar angle, quarter cracks and overall lack of mass. While genetics or the rigors of training can predispose a foot to some of these issues, maintaining the foot in such a way to emphasize mass and durability can go a long way towards minimizing or eliminating these commonly encountered foot problems.

The ideal foot we have all been taught to strive for is rarely found outside of a textbook. Therefore, we must reconsider the wisdom of constantly struggling to emulate something that does not naturally occur. If a foot naturally has a higher heel and steeper hoof angle than the opposing foot, rather than take it off just because it is there we should first consider why it is different from the opposite low heel foot in the first place. The internal characteristics of a foot, including bone angle, soft tissue parameters, palmar angle, etc., dictate the exterior appearance. Attempting to sculpt the seemingly out of balance exterior to meet our own perceived ideals without thought to what is happening internally often puts undue stress on internal components, which can cause inherent problems that are only compounded by the rigors of the horse's racing career.

Dr. Raul Bras is a certified journeyman farrier and veterinarian in the podiatry department at Rood and Riddle Equine Hospital. A member of the International Equine Veterinarian Hall of Fame, Bras graduated from Ross University and completed the farrier program at Cornell University. He is a partner at Rood and Riddle.

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