Optimising the Care and Management of Your Equine Athlete- Part 3

Follow this 5 part blog over the next few weeks for expert advice,  research and essential tips on care and management of your competition horse.

Part 3- Environmental Factors

Susan Stover, DVM, PhD, Dipl. ACVS, is the director of the J. D. Wheat Veterinary Orthopedic Research Laboratory in the UC Davis School of Veterinary Medicine. She is an internationally recognized expert in the field of racehorse injuries and has spent a number of years studying the reasons for death and injuries among racehorses in order to develop prevention strategies.

Significant progress has been made in discovering the causes of catastrophic injury in racehorses and we now have a better understanding of the events leading to bone fracture along with better techniques to detect stress fractures in live horses. Stover and her team have identified race surface and exercise factors that place horses at increased risk for catastrophic injury and have provided horseshoe recommendations to prevent suspensory apparatus injury.

Performance horses incur a wide variety of athletic injuries that are unique to their particular athletic pursuit. Stover and her research team are working hard to discover risk factors, preventive measures, and effective treatments for these athletes.

Injuries to structures that support the fetlock and digit (suspensory ligament, superficial and deep digital flexor tendons) are the primary causes of performance limitations in show jumpers, dressage horses, and eventing horses. The likelihood of injury to these structures increases with increasing limb loads, as might occur with harder surfaces or higher or more difficult jumps. High limb loads induce extremes of carpal (knee), fetlock, and coffin joint hyperextension and can cause damage to the supporting tendons and ligaments.

While several factors affect limb loads and limb biomechanics, a key factor that can be managed for injury prevention is the arena surface that horses are performing on. There is some evidence to support the association of surface with injury and the role of surface in limb biomechanics. Unfavorable ground conditions (soft or heavy ground) were associated with failure to complete the Grand National event. In a study of hoof landing in elite jumping horses, differences were observed between sand and turf surfaces. Differences were also found in hind-limb fetlock motion and hoof slide of racehorses between a dirt and a synthetic track surface, and forelimb dynamics in horses between turf and synthetic surfaces.

In elite dressage horses, fetlock hyperextension was greater on the synthetic surface than the dirt surface (note the opposite result to that found in racehorses).

Surface characteristics affect maximum limb loads, loading rates, and hoof accelerations. Forces associated with these loads and accelerations spread up the limb, with higher loads and forces causing greater joint extensions and higher tendon and ligament strains. Superficial digital flexor tendon strains differed in horses traveling on asphalt, sand and synthetic surfaces. Epidemiological evidence for racehorses on flat surfaces indicates that racetracks and race surfaces appear to affect risk for racehorse injury. Although the results of different studies are somewhat inconsistent relative to which types of surfaces have the greatest risk for injury, two larger scale studies found that injury risk in racehorses was higher for dirt surfaces than for synthetic surfaces.

In a recent study with elite dressage horses, fetlock joint and hoof motion were compared between dirt and synthetic dressage arena surfaces. We found that fetlock hyperextension was greater on the synthetic surface than the dirt surface (note the opposite result to that found in racehorses). In addition, the synthetic surface had a higher load rate than the dirt surface (note the opposite result to that found in some racehorse surfaces). We found that the hoof of dressage horses at an extended trot interacts with surfaces very differently than galloping racehorses.

Not all dirt and synthetic surfaces would produce the same result, however, because surfaces vary markedly in their physical characteristics. The research study also measured the physical characteristics of the surfaces because this information is most useful in designing new surfaces for injury prevention. Thus, there is a need to customize surfaces for individual horse occupations.

Given the high relevance and broad interest in arena surfaces and the large financial investment associated with ring installation, the equine community would greatly benefit from footing recommendations based on science, with the long-term goal of establishing mixtures and management ideal for each discipline. This work could significantly impact wastage in the industry and reduce the need for medications to alleviate pain and inflammation in the performance horse.

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Reprinted from The Horse Report (Spring 2014) with permission from the Center for Equine Health, School of Veterinary Medicine, University of California, Davis (UC Davis).