You've probably heard the old adage from mule fanciers: "Mules is just different." Well, it seems that the same principle holds among racehorses; racing Quarter Horses, it seems, are just different. From racing Thoroughbreds, that is. Researchers presented results from their study of racing Quarter Horse injuries and horseshoe toe grabs at the 2009 American Association of Equine Practitioners (AAEP) convention, held Dec. 5-9 in Las Vegas, Nev., revealing that they found very different effects of toe grabs than researchers found in previous research on racing Thoroughbreds.
Catastrophic injuries in horse racing seem to be attracting more attention from media and researchers these days. The increase in research directed toward reducing the incidence and severity of racing injuries is certainly a good thing, and it has resulted in some safety-oriented regulations and recommendations for Thoroughbred racing (such as mandates to use particular track surfaces and shoeing practices deemed safer than others).
While it might be tempting to extend those Thoroughbred flat-racing recommendations to all racehorses, recent research suggests that this might not be advisable. At the AAEP convention, Mark Martinelli, DVM, MS, PhD, Dipl. ACVS, of California Equine Orthopedics in San Marcos, Calif., discussed the results of a study on the relationship between toe grabs on horseshoes and catastrophic injury in racing Quarter Horses.
A toe grab is a raised rim on the toe area of a horseshoe; its purpose is to help the horse "dig in" to the track and reduce slipping (much like football or baseball cleats). However, there are increased stresses on the limbs from this stronger grip on the ground and quicker "stops" of the feet when they land (normally the foot slides forward just a bit on the ground before stopping, but toe grabs arrest this slide). It's also been suggested that toe graps add stress to the limb by raising the toe relative to the heel. Toe grabs on front feet have been associated with increased incidence of catastrophic injury in Thoroughbreds in at least four studies, reported Martinelli. (Editor's Note: Research by Sue Stover, DVM, PhD, Dipl. ACVS, of the University of California, Davis, has demonstrated that "high" toe grabs on front shoes make a Thoroughbred 16 times more likely to suffer a catastrophic injury while racing.)
However, many jockeys and trainers in the racing Quarter Horse industry feel that toe grabs on front feet are not a risk. In fact, they feel toe grabs are essential for reducing slipping as Quarter Horses break from the gate. Slipping at the gate carries a risk of injury not only to the horse that slips, but possibly also to other horses he might fall into and to his jockey (who might be unseated by the slip).
"When some people found out I was doing this study, they begged me not to let any racing jurisdiction take toe grabs away from Quarter Horses," Martinelli commented.
This study did not find a protective effect of toe grabs, but it didn't find any elevated risks of injury when using them, either. For the study, investigators measured toe grab height on horses suffering catastrophic injury at a California track over a two-year period. They compared these values with those for all 1,314 Quarter Horses racing at a California track during January and June 2008, and they saw no significant difference in the distribution of toe grabs between the two groups (one would have expected a higher percentage of the fatally injured horses to have toe grabs if they were a problem).
Why the difference between Quarter Horses and Thoroughbreds?
Martinelli suggested several differences between racing Quarter Horses and Thoroughbreds, any or all of which might contribute to differences in risk factors for injury.
- Contrary to some long-held beliefs, Quarter Horses appear to pull with their forelimbs when launching from the gate, unlike Thoroughbreds. Martinelli showed several slow-motion videos of Quarter Horses and Thoroughbreds breaking from the gate, demonstrating: "In the case of the Quarter Horse starting a sprint race, the toes dig into the track and the fetlock and carpus (knee) remain flexed (bent) during the first several strides. Thoroughbreds, conversely, tend to land flat-footed and hyperextend the fetlock within the first stride from the gate." Supporting this concept are Martinelli's observations of shoulder musculature in these horses. "Of any breed I work on, there is no discipline that has definition of shoulder musculature like a racing Quarter Horse," he commented. "The deltoids and triceps, which are responsible for shoulder movement, are very well developed in these horses ... the hypertrophy of these muscles in Quarter Horses is amazing."
- Quarter Horses race at shorter distances (often 440 yards, one-quarter mile, or less) and higher speeds (47+ miles per hour vs. 30+ mph for Thoroughbreds). They tend to get faster with each segment of these short races, while Thoroughbreds running longer distances get faster toward the middle of the race, then fatigue and slow down.
- Despite breeding for faster horses, Thoroughbreds don't appear to be getting faster, while Quarter Horses are. (A study published in the Journal of Experimental Biology suggests that a plateau has been reached in the performance of racing in Thoroughbreds.) Six new world records have been set by Quarter Horses racing in the last two years. "As athletic performance gets more and more intensive (in any species/discipline), chances are you'll see more injuries just from the increased physical stress," he commented.
- The two breeds tend to respond differently when they do get injured, he observed. When Thoroughbreds suffer a catastrophic injury, they often fall and roll, while Quarter Horses that suffer injuries resulting in euthanasia more often misstep, then keep running while the jockeys fight to slow them down.
"Factors involved with catastrophic injuries in racing Quarter Horses have not been studied to the same degree as those in Thoroughbreds," Martinelli summarized. "Our recommendation is that the American Quarter Horse Association continue to study these horses and make sure any rules applied to them take into account the differences between racing breeds."
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.
