Track Surface Conditions Influence Likelihood of Racing Fractures

Track surface conditions play an important role in the risk of bone fractures in racing Thoroughbreds. Unfavorable conditions of turf and dirt impair the natural shock-absorbing mechanisms of the equine limb, increasing the likelihood of a career-ending fracture.

In an article published in the Japan Racing Journal, Masa-aki Oikawa, DVM, PhD, recently reported that as turf courses become wetter and softer, fracture risk is reduced. In contrast, muddy conditions on dirt courses lead to a greater risk of horses sustaining a fracture.

Oikawa, a researcher at the Japan Racing Association's Equine Research Institute, noted that although several biological and non-biological factors contribute to racehorse injuries, some are more important than others. "The conditions of the track surface have a major influence on the occurrence of fractures in horses during training and racing," he said.

Using records from the Japan Racing Association and the Racehorse Information Management System, Oikawa analyzed data from 1987 to 2000 regarding track conditions, racing times, and fractures sustained during flat races on Japanese turf and dirt tracks. After examining the outcomes of 556,705 horses, he determined that the incidence of fracture was 1.83% for the 14-year period.

To evaluate the effects of various track conditions on speed, Oikawa compared racing times for 50,564 horses in 4,117 races held in Japan between 1990 and 1994. Distances run varied from 1,200 to 2,500 meters on turf courses, and from 1,200 to 1,800 meters on dirt courses.

Statistical analysis revealed that for turf courses, racing times became slower and fracture risk was diminished as track conditions changed from "firm" to "soft." Oikawa explained, "A moist, soft track means less impact on the horses' legs, which means less speed and fewer accidents."

In contrast, racing times on Japanese dirt courses became faster, and the risk of fracture increased, as track conditions changed from "fast" to "muddy." According to Oikawa, "The high water content of a muddy track causes the overlying sand layers to thin; exposing the hard track bed beneath. Hard tracks provide less cushioning, but more speed."

As track conditions deteriorated from "muddy" to "sloppy," race times on dirt courses grew slower and the risk of fracture was further increased. "Horses have more difficulty running on sloppy tracks than on muddy tracks due to the excessive surface water," Oikawa said. "Sloppy tracks place a greater physiological demand on the horse and can contribute to fatigue-related stumbling."

Optimizing the cushioning capacity of track surfaces reduces fracture risk in racehorses. Oikawa's research suggests that the cushioning capacity of turf racecourses is maximal when the water content of the track surface is maintained above a specific level. Cushioning capacity of dirt courses, on the other hand, is optimized when excess water is eliminated from the track surface.

About the Author

Rallie McAllister, MD

Rallie McAllister, MD, grew up on a horse farm in Tennessee, and has raised and trained horses all of her life. She now lives in Lexington, Ky., on a horse farm with her husband and three sons. In addition to her practice of emergency and corporate medicine, she is a syndicated columnist (Your Health by Dr. Rallie McAllister), and the author of four health-realted books, including Riding For Life, published by Eclipse Press and available at www.ExclusivelyEquine.com or by calling 800/582-5604.

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