High-speed exercise history and catastrophic racing fracture in Thoroughbreds

Leah Estberg From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Leah Estberg in
Current site
Google Scholar
PubMed
Close
 DVM, MPVM
,
Susan M. Stover From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Susan M. Stover in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Ian A. Gardner From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Ian A. Gardner in
Current site
Google Scholar
PubMed
Close
 BVSc, MPVM, PhD
,
Christiana M. Drake From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Christiana M. Drake in
Current site
Google Scholar
PubMed
Close
 PhD
,
Bill Johnson From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Bill Johnson in
Current site
Google Scholar
PubMed
Close
 DVM
, and
Alex Ardans From the Departments of Medicine and Epidemiology (Estberg, Gardner), Anatomy, Physiology, and Cell Biology (Slover), Division of Statistics (Drake), and Calilornia Veterinary Diagnostic Laboratory System (Johnson, Arrians). School of Veterinary Medicine, University of California. Davis, CA 95616.

Search for other papers by Alex Ardans in
Current site
Google Scholar
PubMed
Close
 DVM, MS

Abstract

Objective

To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds.

Animals

64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants.

Procedure

Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by paired t-test and studied in detail using conditional logistic regression.

Results

High total and high average daily rates of exercise distance accumulation within a 2-month period were associated with higher risks for FSI during racing, yet career patterns, such as age at first race or total proportion of career spent laid up, were not found to be associated with risk for FSI. A horse that had accumulated a total of 35 furlongs of race and timed-work distance in 2 months, compared with a horse with 25 furlongs accumulated, had an estimated 3.9-fold increase in risk for racing-related FSI (95% confidence interval = 2.1, 7.1). A horse that had accumulated race and timed-work furlongs at an average rate of 0.6 furlong/d within a 2-month period, compared with a horse with an average of 0.5 furlong/d, had an estimated 1.8-fold increase in risk for racing-related FSI (95% confidence interval = 1.4, 2.6).

Conclusions and Clinical Relevance

Thoroughbred racehorses that either accumulate large total highspeed distances or rapidly accumulate high-speed distances within a 2-month period may be at increased risk for FSI during racing. (Am J Vet Res 1996;57:1549–1555)

Abstract

Objective

To investigate the relation between several racing speed history characteristics and risk of fatal skeletal injury (FSI) in racing Thoroughbreds.

Animals

64 Thoroughbreds euthanatized during a 9-month period in 1991 at a California racemeet because of a catastrophic fracture incurred while racing (cases), identified retrospectively. For each race in which an FSI occurred, 1 control horse was randomly selected from the noncatastrophically injured participants.

Procedure

Racing and officially timed workout histories were obtained for each horse. Several history characteristics were calculated to summarize racing career patterns and high-speed exercise schedules prior to date of injury and included age at first race, proportion of career spent laid up, average duration of laid up periods, average lifetime racing frequency, time from last lay up to date of injury, and total and rate of distance accumulated 1 to 6 months prior to date of injury. History characteristics associated with FSI were screened by paired t-test and studied in detail using conditional logistic regression.

Results

High total and high average daily rates of exercise distance accumulation within a 2-month period were associated with higher risks for FSI during racing, yet career patterns, such as age at first race or total proportion of career spent laid up, were not found to be associated with risk for FSI. A horse that had accumulated a total of 35 furlongs of race and timed-work distance in 2 months, compared with a horse with 25 furlongs accumulated, had an estimated 3.9-fold increase in risk for racing-related FSI (95% confidence interval = 2.1, 7.1). A horse that had accumulated race and timed-work furlongs at an average rate of 0.6 furlong/d within a 2-month period, compared with a horse with an average of 0.5 furlong/d, had an estimated 1.8-fold increase in risk for racing-related FSI (95% confidence interval = 1.4, 2.6).

Conclusions and Clinical Relevance

Thoroughbred racehorses that either accumulate large total highspeed distances or rapidly accumulate high-speed distances within a 2-month period may be at increased risk for FSI during racing. (Am J Vet Res 1996;57:1549–1555)

Advertisement