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The results of a landmark, three-year study on radiographic changes in Thoroughbred yearlings will be presented during the American Association of Equine Practitioners annual convention, which will be held in San Antonio, Texas, Nov. 26-29. Included in the report will be the effect of these changes on future racing performance, writes Stephanie L. Church in the November edition of The Horse.

"It's the first study of its kind in Thoroughbreds, and the most comprehensive study of radiographic changes in horses," said Dr. Al Kane of Colorado State University. Kane conducted the study at Colorado State's Equine Orthopaedic Research Laboratory under the direction of AAEP president-elect Dr. Wayne McIlwraith.

Researchers examined the radiographs of 1,200 Thoroughbred yearlings from sales conducted by Keeneland and the Fasig-Tipton Company in Kentucky from 1993-96. Kane and his colleagues reviewed and categorized changes in the horses' joints, including fetlocks, knees, hocks, and stifles. A two-part follow-up was performed. Researchers consulted racing records from The Jockey Club Information Systems, and also mailed questionnaires to buyers of the yearlings. The race record follow-up is complete.

"We found out whether or not the horses started, the percentage of starts the horses placed in, and how much money was won by the horses during the 2- and 3-year-old years," Kane said.

As a result of the study, the CSU team has been able to identify that certain radiographic changes have a negative effect on performance and that other changes that caused veterinarians concern before this study clearly do not have an effect.

"Some of the changes (which had a negative effect on race record) are not the lesions that would normally come to mind," Kane said. "There are some new changes we should look at closer."