Horse‐level risk factors for fatal distal limb fracture in racing Thoroughbreds in the UK

Abstract

Summary Reasons for performing study: Fractures below the level of the radius or tibia (distal limb fractures) are the most common cause of equine fatality on UK racecourses; however, little is known about their epidemiology or aetiology. Identification of risk factors could enable intervention strategies to be designed to reduce the number of fatalities. Objectives: To identify horse‐level risk factors for fatal distal limb fracture in Thoroughbreds on UK racecourses. Methods: A case‐control study design was used. Fractures in case horses were confirmed by post mortem examination and 3 matched uninjured controls were selected from the race in which the case horse was running. One hundred and nine cases were included and information was collected about previous racing history, horse characteristics and training schedules. Conditional logistic regression was used to identify the relationship between a number of independent variables and the likelihood of fracture. Results: Horses doing no gallop work during training and those in their first year of racing were at significantly increased risk of fracture on the racecourse. Case horses were also more likely to have trained on a sand gallop, i.e. a gallop described by trainers as being primarily composed of sand. Conclusions: Modifications to training schedules, specifically within the first year of racing, may have a large impact on the risk of fatal distal limb fracture on the racecourse. Horses should do some gallop work in training and our results suggest that the minimum distance galloped should be between 805‐2012 m (4‐10 furlongs)/week. Potential relevance: The information from this study can be used to alter training schedules in an attempt to reduce the incidence of fatal distal limb fracture in Thoroughbred racehorses. Training should include some gallop work, and further studies, recording the exact level of work, will help to identify an optimum range of training speeds and distances which will reduce the liklihood of catastrophic fracture on the racecourse.

Risk factors for equine fractures in Thoroughbred flat racing in North America

“…In our study a higher risk of injury was found for older horses. The age of the horse has been shown to be associated with the risk of injury in a number of studies (Estberg et al, 1996b;Bailey et al, 1997;Cohen et al, 1997;Cohen et al, 2000;Parkin et al, 2004a;Perkins et al, 2005). This consistent association might be because older horses continue to accrue microdamage and injury risk.…”

“…The risk of fracture was also higher for horses that did no gallop work during training (Parkin et al, 2005) but horses that accumulated an excess timed work distance within a 2 month period prior a race were at higher risk as well (Estberg et al, 1996a). Exercise history (Estberg et al, 1996a,b;Estberg et al, 1998a,b) (Cohen et al, 2000) (Hernandez et al, 2005;Parkin et al, 2005) and specifically the distance galloped in training (Estberg et al, 1995;Estberg et al, 1996a,b;Estberg et al, 1998a,b;Cohen et al, 2000;Parkin et al, 2004a) have also been associated with injuries.…”

Determination of factors affecting the length of racing career of Arabian horses in Turkey

“…There are various factors influencing the length of racing career of horses. Although musculoskeletal injuries are considered to be the major reason for career ending (2,3,26,38), studies showed that many other risk factors such as age at first start (37), gender (14), exercise intensity (14,24), race distance (25), track condition (1) are also related with career ending.…”

Fracture incidence rates and the association of rest with bone remodelling in Thoroughbred racehorses at the Hong Kong Jockey Club

“…Parkin, Clegg et al (2004c) reported that horses which did zero fast work were 3.13 times more likely to have catastrophic fracture of the distal limb compared to horses which galloped two to 7 furlongs per week (95% CI 1.10 -8.91, P = 0.03). Short distances of gallop work were also shown to be protective against fracture and further supported by two other United Kingdom studies (Verheyen, Price et al 2006a, Verheyen, Newton et al 2006b).…”

“…Two retrospective case control studies showed the risk of distal limb catastrophic fracture (OR 3.1, 95% CI 1.1 -8.9, P = 0.02, Parkin, Clegg et al 2004c) and in particular with lateral condylar fractures was greatest for horses which accumulated zero furlongs per week (OR 5.26, 95% CI 1.86 -14.90, P = 0.002, Parkin, Clegg et al 2004b). In contrast to the Kentucky study, the United Kingdom studies also reported the age at first racing start which takes into account when racehorses were most adapted to start a race (Parkin, Clegg et al 2004b, Parkin, Clegg et al 2004c. Horses which started their racing careers at three or four were at greatest risk of catastrophic lateral condylar fracture when compared with two year olds (OR 2.71, 95% CI 1.36 -5.42, P < 0.005).…”