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The risk of fatal distal limb fractures in thoroughbreds racing in the UK was calculated and shown to vary considerably between the different types of race. Flat turf racing was associated with the lowest risk (0.4 per 1000 starts) and national hunt flat racing was associated with the highest risk (2.2 per 1000 starts). The types of fracture were classified by detailed radiographic and postmortem examinations of all the cases recorded over two years, and the distribution of the different types of fracture in the five main types of racing was examined. Overall, lateral condylar fractures of the third metacarpus were the most common, and they were also the most common in national hunt-type races (hurdle, steeplechase and national hunt flat races). In all-weather flat racing biaxial proximal sesamoid fractures were most common, and in turf flat racing fractures of the first phalanx were most common. The risk of fractures of more than one bone was greater in national hunt-type races.

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.

SUMMARY The results of a survey are presented in which 589 limbs from 206 horses were dissected. In 174 of the limbs lesions were found in either the superficial (131) or deep (43) digital flexor tendons. Changes occurring with age were also recorded. The sites of the abnormalities and their macroscopical appearance are described and the value of the results is considered in relation to the diagnosis and the treatment of clinical lesions. RÉSUMÉ On présente les résultats d'une étude systématique des tendons de 589 membres provenant de 206 chevaux. Sur 174 membres, on identifia des lésions soit sur les tendons superficiels (131 cas) soit sur les tendons fléchisseurs profonds (43 cas). Des modifications se produisant avec l'âge furent également constatées. Les sites des anomalies et leurs aspects macroscopiques sont décrits. Les résultats sont appréciés pour ce qu'ils peuvent apporter au diagnostic et au traitement des lésions cliniquement identifiables. ZUSAMMENFASSUNG Die Resultate einer Untersuchung werden vorgelegt, die 589 Gliedmassen von 206 Pferden umfasste. An 174 Gliedmassen wurden Laesionen festgestellt, entwederan der oberflächlichen (131) oder an der tiefen (43) Beugesehne. Altersveränderungen wurden ebenfalls vermerkt. Die Lage der Veränderungen und ihr makroskopisches Aussehen werden beschrieben und die Bedeutung der Resultate wird besprochen in Abhängigkeit von Diagnose und Therapie der klinischen Zeichen.

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