UF researchers collaborate with Florida Thoroughbred racing industry in study to shed light on horse injuries

Just like human athletes, horses that race are prone to injury. Now University of Florida researchers report that a horse’s sex, the number of days since its last race and the racing surface itself appear to be associated with risk of catastrophic musculoskeletal injury.

Of every 1,000 Thoroughbreds that race, one or two receive these types of injuries at the track, and most who do are euthanized. Industry representatives say the UF findings supplement a relatively sparse pool of data relating to the national incidence of such injuries and could help identify preventive measures.

The study, which appeared in the January issue of the Journal of the American Veterinary Medical Association, sought to determine the incidence of injuries in racehorses at two Florida racetracks, and to identify risk factors.

UF researchers calculated the incidence of musculoskeletal injuries that occurred for all races held at the two tracks from 1995 to 1998. Race-start characteristics – a variety of factors pertaining to horse, race and track – were compared among 97 Thoroughbreds that were euthanized because of their injuries and 388 horses randomly selected from uninjured participants. For each horse, epidemiological data were collected from official race-day programs and a computerized commercial racehorse database.

Supported by a $10,000 grant from the UF College of Veterinary Medicine and the state’s Pari-mutuel Wagering Research Development Program, the researchers found that geldings were twice as likely as fillies to have musculoskeletal injuries.

“Because of their potential for breeding or sales purposes, females and colts are likely to run less frequently or to be retired from racing sooner than are geldings,” said Jorge Hernandez, D.V.M., Ph.D., an epidemiologist at UF’s veterinary college and the project’s principal investigator.

In addition, horses that had gone 33 or more days since their last race were 2.5 times more likely to be hurt than horses that had waited two weeks or less to race again – possibly because horses that waited longer to race were recovering from other health problems, leaving them susceptible to new injuries.

Both findings support existing data from California studies showing that sex and days since last race are important factors in determining risk of injury to race horses. UF researchers also found, however, that due to a variety of conditions, horses racing on natural grass turf may stand a greater risk of injury at Florida tracks than their counterparts that run on dirt, Hernandez said.

While the significance of this finding is unclear, it does set the Florida study apart from previous studies about the incidence of musculoskeletal injuries that occur at the track.

“It’s not just the track surface, but other conditions that are often present in turf races that may predispose horses running in these races to major musculoskeletal injury,” Hernandez said. “Turf races are typically more competitive than dirt races at Florida racetracks. For example, our study results showed that horses that run on turf are more likely to participate in races with large fields, handicap races, long races and races with high purse values, compared to those running in dirt races.”

Racetrack veterinarian Mary Scollay, D.V.M., who works at Calder and Gulfstream in South Florida, collaborated with Hernandez and others in the project. She said she was surprised by the findings. “I had always believed that a more natural surface would result in safer racing conditions,” she said. “This study suggests that conditions associated with turf racing – not the turf itself – may combine to increase the risk of injury.”

Wayne McIlwraith, B.V.Sc., Ph.D., president of the American Association of Equine Practitioners and director of orthopedic research at Colorado State University in Fort Collins, called the study “an important contribution” but said he was cautious about the researchers’ turf-related finding.

“This study does lay this issue into question, and that is appropriate,” he said. “However, as the researchers themselves pointed out, there are a variety of factors to be considered, including the types of horses that are going to be racing on turf in the first place.”

He added that musculoskeletal disease is perhaps racing’s “biggest single problem.”

“Between studies in New York, California, Kentucky, Texas and now Florida, we now have a fairly consistent idea of the incidence of these injuries,” McIlwraith said. “This gives very useful information to AAEP members in assessing the overall incidence of these injuries.”

He added that the UF study’s other findings relating to the association with sex and days since a horse’s last race confirm findings previously reported in other studies.

“Geldings will generally be raced for a longer period of time because they have no kind of alternative breeding career,” McIlwraith said. “And we’re now realizing that when a horse stops training, their bones get osteoporotic, or decrease in strength and density. So it makes sense that the longer a horse goes between races, the more susceptible it will be to injury.”

Hernandez said a high incidence of musculoskeletal injuries in racehorses over a short period of time can raise questions about safety issues associated with training, racing or track conditions.

“We’ve found that these types of injuries are caused by multiple factors. Now the ultimate goal is to formulate effective injury prevention strategies and reduce the number of horses that ultimately die because of these injuries,” he said.

Another study, funded by the same program, is now in progress to determine whether the use of various shoe modifications often used in race horses, as well as high-speed exercise patterns, are associated with risk of musculoskeletal injury in Thoroughbred racehorses.

Advances in equine sports medicine have enabled many horses to return to competition after sustaining what would have previously been career-ending injuries. Nevertheless, Scollay said, “It is important to remember that no injury is ‘acceptable’ and that medical progress does not eliminate the need for preventing injury whenever possible.

Studies like this one allow more levels of industry participation in risk reduction, and there is no downside to injury prevention – everyone benefits.”