Analysis of horse race videos to identify intra-race risk factors for fatal distal limb fracture

https://doi.org/10.1016/j.prevetmed.2006.01.006Get rights and content

Abstract

The objective of this study was to identify risk factors, during racing, associated with imminent fatal distal limb fracture in Thoroughbreds. One hundred and nine cases of fatal distal limb fracture were identified from all 59 UK racecourses over a 2-year period (February 1999–January 2001). Three uninjured control horses were randomly selected from the same race as the case horse. Videos of races in which fractures occurred were viewed using a defined protocol. Fractures in flat races occurred at any time during the race, whereas 74% (45/61) of cases in national hunt type races occurred in the second half of races. More than 75% (79/103) of cases were spontaneous, i.e. there was no obvious external influence such as a fall at a fence or collision with another horse. Sixty-six percent (44/67) of horses, sustaining a forelimb fracture, fractured the forelimb they were using as lead leg at the time of fracture. When case and control horses were compared, horses that were: (a) making good progress through the race, (b) reluctant to start and (c) received encouragement in the final 10 s before the time of fracture, were more likely to sustain a fracture.

Introduction

The majority of previous studies of racing injuries have focussed on identification of risk factors associated with events prior to the race in which the injury occurs. Characteristics of the horse, previous racing histories and training regimens have all been shown to be associated with an increased risk of injury (Estberg et al., 1996, Estberg et al., 1998, Bailey et al., 1997, Carrier et al., 1998, Cohen et al., 2000, Hernandez et al., 2001). Two previous reports have included details of video analysis of events occurring during racing, but both have their limitations. Ueda et al. (1993) analysed patrol videos of 58 horses that suffered “serious accidents” on racecourses. This study did not include any comparison with uninjured control horses, but did conclude that horses were more likely to injure the lead forelimb than any other limb. They also suggested that injuries were more likely to occur during a change of lead leg and that more injuries occurred in turns, than on straight parts of the course. Cohen et al. (1997) analysed videos of 216 cases of musculoskeletal injury and 532 race-matched controls. They studied the 12-s period prior to fracture and demonstrated that the risk of injury was increased soon after a collision with another horse or soon after a change of lead leg. They also showed that jockeys were less likely to use the whip on case horses and that case horses were more likely to be toward the back of the field after the first two furlongs of a race. As far as the authors of the current study are aware there is no previous report that compares injured and uninjured horses, from the start of races to time of fracture. This paper therefore represents the most comprehensive attempt at identification of events occurring during racing which are associated with fracture.

Section snippets

Case and control definitions

One hundred and nine flat and jump races, which contained a fatal distal limb fracture, were identified from all 59 UK racecourses over a 2-year period. A case was defined as a horse which sustained a fracture of the carpus/tarsus and/or distal limb, during racing, which required euthanasia. Cases were confirmed by post-mortem examination conducted at the University of Liverpool. Three controls per case were selected at random from all uninjured horses, in the same race as the case horse, which

Percentage of race completed

It was possible to identify the exact time of fracture in 94% (103/109) of races. The percentage of the race completed before fracture (time to fracture/time of winner) is shown in Fig. 1. In flat races 57% (24/42) of fractures occurred in the second half of races. In contrast 74% (45/61) of fractures in national hunt type races (hurdle, steeplechase and national hunt flat) occurred in the second half of races. The median percentage of race completed before fracture was significantly greater

Discussion

This paper has identified previously unreported risk factors for fatal distal limb fracture in racing Thoroughbreds. Previous studies have either concentrated on the 12-s period prior to the time of fracture (Cohen et al., 1997) or have not included comparisons with uninjured control horses (Ueda et al., 1993). The current study used a matched case–control design applied to the analysis of whole races from start to the time of fracture.

The precise time and location of injury was recorded for

Acknowledgements

The authors would like to gratefully acknowledge the Jockey Club Veterinary Officers, Michael Whyatt at the Jockey Club, local racecourse vets, racecourse managers and clerks, racehorse owners and trainers and Racecourse Ambulance Services Ltd. This study and Tim Parkin's post at Liverpool University was funded by the Horserace Betting Levy Board.

References (17)

There are more references available in the full text version of this article.

Cited by (0)

1

Present address: Institute of Veterinary, Animal and Biomedical Sciences, College of Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.

2

Present address: The Hong Kong Jockey Club, Sha Tin Racecourse, N.T., Hong Kong.

View full text