Rolex Talk Highlights Performance Horse Issues

The 2006 Rolex Kentucky Three Day Event drew more than 90,000 equine enthusiasts to the Kentucky Horse Park, and Lexington's Hagyard Equine Medical Institute (HEMI) used the opportunity to educate horse owners on common health issues affecting the sport horse.

Duncan Peters, DVM, MS, recently onboard as a member of HEMI's Sporthorse Division, presented "Sport Horse Potpourri--Items of Interest About Your Performance Horse" as part of Hagyard's weekend educational series. Peters is certified by the Fédération Equestre Internationale (FEI) as a veterinarian for dressage, eventing, jumping, and reining competition.

Peters reviewed recent studies pertinent to sport horses:

Morning performance--It has been shown that horses actually have swings in performance that have been referred to as "Morning Glory Syndrome." A recent Italian study looked at the role of hormone levels in the perceived improvement of performance by horses worked in the morning hours as opposed to those worked later in the day. Researchers found that levels of the hormones tryptophan and serotonin, both natural sedatives, were naturally lower in the morning hours and higher in the afternoon.

Peters suggests that horse owners keep these findings in mind when scheduling work times, and they should vary their training regime as much as possible to override the hormonal swing. Peters also noted that hormone levels can change depending on environmental influences such as stress, climate change, etc.

Effect of altrenogest on behavior--A popular choice among competitive equestrians, Altrenogest (marketed as Regumate) suppresses estrus in mares. However, it has also been widely believed that the hormone has favorable side effects upon behavior and physiology, leading some equestrian sport federations to consider banning the drug for any use. Australian researchers at the University of Sydney have shown that oral altrenogest, given over a period of eight weeks, had no impact on the dominance, social hierarchy, activity level, body mass, or body condition scores of mares. Altrenogest is allowed in mares only for FEI and for all horses, excluding endurance horses, in  United States Equestrian Federation competitions.

Shock wave therapy demonstrates significant analgesic properties--Scientists have shown that extracorporeal shock wave therapy (ESWT), which involves the use of pulsed acoustic waves to speed healing, has a numbing effect on the area on which it is used. Researchers have determined that the horse may lose significant sensation in the area for up to 35 days due to damage to the myelin sheath of the palmar digital nerves. Peters suggests that ESWT should only be used on a horse that is well diagnosed and is in a controlled exercise program, as the numbness may hide serious lameness and potentially lead to catastrophic injury.

Support given by boots and wraps--Whether winding a polo wrap or sticking the Velcro of a performance boot, horse owners across disciplines use leg wear to support and protect their horses during exercise.  Many research studies have determined just how much concussion those wraps and boots really absorb: polo wraps and racing or standing bandages were each shown to absorb around 1% of the force sustained by the legs of a 1,000-pound horse. Sport boots with a neoprene tab that cradles the suspensory were only marginally better, at 5-7%. Peters pointed out that while this study demonstrates that horse owners cannot look to boots or wraps for significant support, they do provide protection against bumps and bruises.

A rider's influence on lameness--Your horse gallops around his pasture, looking sound, fit, and ready to ride. But as soon as you mount up, that little bobble starts. There's no denying it--he's lame. Is your riding skill (or lack thereof) to blame? Austrian researchers at the University of Veterinary Medicine in Vienna tackled this issue, measuring the exact movement of twenty horses while being trotted in hand and ridden by both an experienced dressage rider and a novice. Eleven horses showed significant differences in forelimb lameness when ridden, while four showed a difference in hind limb lameness. As for the effect of rider skill level, experienced dressage riders were more likely to exacerbate a hind limb issue than novices. Therefore, veterinarians might find it helpful to analyze a suspected lame horse both in-hand and under saddle. Two individuals should ride the horse if rider interference is suspected.

Performance capacity and girth tension- Peters discussed the "tremendous effect on fatigue and recovery rates" seen in horses outfitted with girths featuring elastic components or traditional girths (without elastic) that are kept slightly loose. For more information on girth tension and its effects on the performance horse, see:

Age and training have no effect on jumping style- A Dutch study has concluded that  the jumping style exhibited by a horse at six months of age will not change, regardless of age or training. Peters said these findings are important to those searching for a prospect, as they suggest that a horse who has an undesirable jumping style will not "grow out of it," nor be changed significantly by training. For more information, see:

Phenylbutazone is just as good in moderation- Oklahoma State University researchers have determined that a four gram dose of Bute gives no additional benefit in cases of lameness than a two gram dose, and may speed the onset of possible dangerous side effects, including gastric ulcers, kidney damage and colitis. "Bute is really the gold standard," Peters said, "but if misused it can be devastating." For more on the possible side effects of Bute, see:

Dr Peters further covered topics of new joint therapies, MRI findings, transportation concerns and other aspects of interest to sporthorse owners.

Other topics presented during Hagyard's lecture series at the Rolex Three Day Event include sport horse diagnostics and large animal emergency response.

About the Author

Erin Ryder

Erin Ryder is a former news editor of The Horse: Your Guide To Equine Health Care.

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