"Forelimb conformation receives lots of attention because of perceived predisposition to injury (with various conformational problems)," began Liz Santschi, DVM, Dipl. ACVS, clinical associate professor at the University of Wisconsin-Madison, at the Western Veterinary Conference held Feb. 20-25 in Las Vegas, Nev.

Thoroughbred Foals

She discussed a conformation study that she is planning to submit for publication. In her study, nearly all racing-bred Thoroughbred foals were carpus valgus (knock-kneed) at birth, many toed out, and a few had offset knees. But at about 18 months of age, nearly two-thirds had offset knees and the incidence of knock knees had dropped by a large margin. Less than 10% had completely straight forelimbs at any age, and more than half had more than one conformational deviation.

Another finding was that heavier birth weight of the foal was associated with offset carpal conformation at every age.

To look at the genetics of conformation, her study also evaluated conformation of the foals' sires and dams whenever possible. She found several associations between carpal conformation of the parents and that of the offspring. "So it took me a long time to prove what everyone already knows," she said with a laugh.

Santschi evaluated the efficacy of conformation correction as well. More information: www.TheHorse.com/ViewArticle.aspx?id=5604.

Thoroughbred Racehorses

Santschi also discussed her yet unpublished study on Thoroughbred racehorse conformation. To quantify the frequency of conformational problems in the average Thoroughbred, she evaluated forelimb conformation, height, weight, sale price, and racing performance of nearly 300 horses in a 2-year-old sale.

She reported that about half of the racehorses exhibited multiple conformation defects, and that this was quite common in broodmares as well. Only about a quarter of the horses evaluated had straight knees, and only about half had straight fetlocks. Some conformational problems were strongly associated.

Santschi found an association between carpal conformation and the number of starts in the 2-year-old year (horses that were valgus and outwardly rotated in their knees made more starts). At two to four years of age, toed-in fetlock conformation was associated with likelihood of winning, and with likelihood of winning a greater percentage of races.

She concluded that straight forelimb conformation is overrated, and valgus (knock-kneed) conformation by itself is not desirable. "Deviation from straight conformation in the forelimb is common in 2-year-old Thoroughbreds sold as racing prospects, and not all deviations have a similar impact on limb motion and early athletic performance," she stated.

"The problem with conformation and performance is that conformational evaluation is subjective, and the rules are largely based on anecdotes," she went on. "There are very few straight horses where you can't find any fault in their conformation at all, and lots of crooked horses that run quite fast.

"Evaluating a yearling and predicting future performance is like looking into a middle school yard and picking the track star," she explained. "You are going to pick some slow runners, and you are going to miss a few fast ones. Conformation evaluation is about narrowing the possible pool."

For more information, see www.TheHorse.com/ViewArticle.aspx?id=5701.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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