Abstract: 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.

Abstract: Stereotypies are invariant and repetitive behaviour patterns that seemingly have no function, which tend to develop in captive animals faced with insoluble problems and may be indicative of reduced welfare. A 4 year prospective study of the factors influencing the development of stereotypic and redirected behaviours (abnormal behaviour) in a population of 225 young Thoroughbred and part-Thoroughbred horses was conducted between 1995 and 1999. Abnormal behaviour affected 34.7% of the population. Multivariable analysis showed that foals of low- or middle-ranking mares were less likely to develop abnormal behaviour than foals of dominant mares (rate ratio (RR) 0.23, P<0.01; RR 0.48, P<0.01, respectively). Weaning by confinement in a stable or barn was associated with an increased rate of development of abnormal behaviour, compared with paddock-weaning (RR 2.19, P<0.05), and housing in barns, rather than at grass after weaning, was associated with a further increase (RR 2.54, P<0.01). Specific stereotypic and redirected behaviours were then considered as separate outcomes. Crib-biting was initiated by 10.5% of horses at median age 20 weeks, weaving by 4.6% of horses at median age 60 weeks, box-walking by 2.3% of horses at median age 64 weeks and wood-chewing by 30.3% of horses at median age 30 weeks. Wood-chewing developed at a lower rate in horses born to subordinate or mid-ranking mares than in horses born to dominant mares (RR 0.29, P<0.01; RR 0.41, P<0.01, respectively), and at a higher rate in horses kept in barns or stables rather than at grass after weaning (RR 4.49, P<0.001; RR 1A6, P<0.001, respectively). Feeding concentrates after weaning was associated with a 4-fold increase in the rate of development of crib-biting (RR 4.12, P = 0.02). The results of this study support the idea that simple changes in feeding, housing and weaning practices could substantially lower the incidence of abnormal behaviour in young horses.