University of Wisconsin researchers have shown that certain forelimb characteristics in the growing foal are associated with higher birth weights, and a foal's carpal (knee) conformation is associated with the carpal conformation of both of its parents. Additionally, they implicate both genetics and the environment in the forelimb conformation of a Thoroughbred foal.

"Forelimb conformation is a topic often discussed among veterinarians and trainers and its potential impact on athletes, but there is little scientific evidence to go along with anecdotal theories as to the origin of these conformational flaws, and which horses are at risk to develop them," said Scott Leibsle, DVM, who presented the study findings at the 2005 AAEP Convention in Seattle, Wash., on Dec. 6. He and his co-authors aimed to identify factors that might contribute to or influence conformational development.

"The ultimate goal here is to try and maximize the athletic potential of each horse, with us as veterinarians intervening as minimally as possible," Leibsle added.

The authors recorded the conformation changes (subjective measurements) of foals every 30-60 days until the foals reached 18 months of age and were sold at the yearling sales. They recorded body weights and noted whether the knees were straight, knock-kneed, offset, or turned out. Fetlock conformation was graded as straight, inwardly rotated, or outwardly rotated. The authors also graded the parents' conformation whenever possible.

Heavy birth weights were significantly associated with offset carpal conformation and inward fetlock deviation, which suggests that (although not proven) early heavy loads might have an impact on conformation. Similar carpal conformation of the sires was significantly associated with yearling outward carpal rotation and offset knees, and dam carpal valgus (knock knees) had a very strong trend of association with yearling valgus.

There were no associations for fetlock conformation between parents and progeny. "This may mean there are some additional (environmental) factors associated with the development of the fetlock," Leibsle said. "Conformational development is a multifactorial, dynamic process, and we need to perform some further experimentation with broader factors and a larger number of foals."

Leibsle hopes this information will help veterinarians and horse owners more accurately predict how a foal's conformation will change as it matures, allow for earlier intervention if the foal requires surgery, and avoid surgery if the foal will correct spontaneously.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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