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Background: Early‐life locomotor activity during turn out may alter susceptibility to musculoskeletal disease and injury via modulation of behaviours and tissue development during growth. Objectives: Investigate associations between turn out practices and rates of musculoskeletal disease and injury in young Thoroughbreds on stud farms in the United Kingdom. Study design: Prospective cohort. Methods: Daily records were kept on location and duration of turn out for 134 Thoroughbred foals on six stud farms, from birth until leaving the farm or study exit. Data on veterinary‐attended episodes of musculoskeletal disease or injury were collated concurrently. Average daily turn out times (hours), areas (acres) and group size (n foals) were calculated for rolling 7‐ and 30‐day periods of age. Multivariable Cox regression, including farm as a random effect, was used to investigate associations between turn out practices and musculoskeletal disease and injury. Results: The overall incidence of musculoskeletal disease or injury was 5.3 cases/100 foal‐months at risk (95% confidence interval [CI]: 4.2–6.6). Compared with 24/7 turn out, average daily turn out times of between 9 and 23 hours over a 7‐day period were associated with a 4.6‐fold increase in musculoskeletal injury rate (95% CI: 1.7–12.3; P < 0.001), adjusting for farm and paddock area. Each 1‐acre increase in the average daily turn out area during the 4th month of life, reduced the rate of musculoskeletal disease and injury between 6 and 18 months of age by 24% (hazard ratio 0.76, 95% CI: 0.58–0.99; P < 0.001), adjusting for farm and turn out time. Main limitations: Non‐random sample of participants may affect generalisability. Use of veterinary‐attended events likely underestimates disease/injury rates. Conclusions: Results suggest that disruptions or alterations to turn out time routines increase injury risk and should be avoided where possible. Turn out in larger paddocks, particularly before weaning, may confer protection against subsequent musculoskeletal disease and injury. [ABSTRACT FROM AUTHOR]

Background: Racehorses are at an increased risk of stress fracture within the first 12 months of racing and when resuming training after a break. Research in these high‐risk periods and on the effect of performance post‐recovery is limited. Objectives: To describe the occurrence of stress fractures, diagnosed by nuclear scintigraphy (NS), in racehorses' first 12 months training in Hong Kong, and their impact on racing performance and career length. Study design: Retrospective 1:2 matched case‐control study. Methods: Clinical records of horses with NS‐diagnosed stress fractures within 365 days of import between 2006 and 2018 were collated. Cases and controls were matched on import date. Univariable conditional logistic regression compared signallment, pre‐fracture training and post‐recovery racing performance between cases and matched controls. Shared Frailty Cox regression analysed time from import to fracture and total career length. Results: Eighty‐seven horses sustained a NS‐diagnosed fracture within their first year in Hong Kong (incidence risk 1.7% [95% confidence interval (CI) 1.4%‐2.1%; N = 5180]). The humerus (42.0%; 95% CI 31.8%‐52.6%; n = 39) and tibia (28.0%; 95% CI 19.1%‐38.2%; n = 26) were the most common stress fracture sites. Cases missed a median of 63 days (Interquartile range (IQR) 49‐82) of training because of fracture. Within the 12 months following diagnosis, case horses had a median of four (IQR 2‐4, P <.0001) fewer race starts and were down HK$ 206 188 (IQR HK$ 0‐436 800, P =.007) in race earnings compared to controls. Career length did not significantly differ between cases and controls (median 2 years and 3 months; IQR 15.3‐39.1 months; P =.2). Main limitations: Only stress fractures diagnosed by NS were included, hence, the study is not representative of all stress fractures occurring in racehorses in Hong Kong. Conclusions: Racehorses sustaining a stress fracture within 1 year of entering Hong Kong lost significant time in training, earnings and race starts. However, overall career length was unaffected. [ABSTRACT FROM AUTHOR]

This study aimed to determine the effects of exercise on racecourse performance in horses racing on the flat. Daily exercise and race records were obtained over a 2-year period for a cohort of racehorses in training for which injury data were also available. Multivariable regression techniques were used to investigate associations between canter, training gallop and race distances accumulated in the 30 days prior to each race and the odds of winning the race, earning prize money and the amount of prize money won. Higher cumulative high-speed (gallop + race) distances were associated with increased likelihood of winning a race and earning prize money. Having raced in the previous 30 days increased the odds of winning. There was an interactive effect of distance cantered and galloped during training on amount of prize money won, which was also associated with distance raced in the previous 30 days. Taken together with findings from previous injury studies in the same study population, these results indicate that training regimens designed to reduce skeletal injuries are unlikely to adversely affect race performance. [ABSTRACT FROM AUTHOR]

The aim of this study was to identify exercise-related risk factors for carpal and metacarpo- and metatarso-phalangeal (MCPJMTP) joint injury occurrence in young Thoroughbreds in fiat race training. In a 2-year prospective cohort study, daily exercise and joint injury data were collected from horses in 13 training yards in England. Four injury categories were defined: (1) localised to a carpal or MCP/MTP joint based on clinical examination and/or use of diagnostic analgesia with no diagnostic imaging performed; (2) localised to a carpal or MCP/MTP joint with no abnormalities detected on diagnostic images; (3) abnormality of subchondral bone and/or articular margin(s) identified using diagnostic imaging; (4) fracture or fragmentation identified by diagnostic imaging. Multivariable Cox regression analysis was con- ducted to determine risk factors for injury occurrence, by type (carpal or MCP/MTP) and category. Exercise distances at canter and high speed in different time periods were modelled as continuous time-varying variables. A total of 647 horses spent 7785 months at risk of joint injury and 184 injuries were recorded. Increasing daily canter distance reduced the risk of Category 1 and Category 3 injuries whereas greater 30-day canter distances increased Category 4 injury risk. More weekly high-speed exercise increased Category 1 injury risk. MCP/MTP injury risk reduced with increasing daily canter distance but increased with accumulation of canter or high-speed exercise since entering training, whereas accumulation of canter exercise was marginally associated with reduced carpal injury risk. Risk of all injury types varied significantly between trainers. The results of this study suggest that regular canter exercise is generally beneficial for joint health, while accumulation of high-speed exercise detrimentally affects MCPJMTP joints. [ABSTRACT FROM AUTHOR]