Centre for Applied One Health Research and Policy Advice, Jockey Club College of Veterinary Medicine and Life Sciences, City University of Hong Kong, Kowloon, Hong Kong SAR.
Equine Hospital, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Midlothian, UK.
Equine Vet J. 2021 May;53(3):460-468. doi: 10.1111/evj.13324. Epub 2020 Oct 2.
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.
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.
Retrospective 1:2 matched case-control study.
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.
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).
Only stress fractures diagnosed by NS were included, hence, the study is not representative of all stress fractures occurring in racehorses in Hong Kong.
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.
赛马在参赛的头 12 个月以及休赛后重新训练时，骨折的风险会增加。对这些高风险时期以及恢复后表现的研究有限。
描述香港赛马在训练的头 12 个月内发生核闪烁扫描（NS）诊断的应力性骨折的情况，以及这些骨折对赛马表现和职业寿命的影响。
回顾性 1:2 匹配病例对照研究。
对 2006 年至 2018 年间进口后 365 天内通过 NS 诊断为应力性骨折的赛马的临床记录进行了整理。根据进口日期对病例和对照组进行匹配。单变量条件逻辑回归比较病例和匹配对照组之间的信号、骨折前训练和恢复后比赛表现。共享脆弱性 Cox 回归分析了从进口到骨折的时间和总职业寿命。
87 匹马在进入香港的第一年中发生了 NS 诊断的骨折（发病率风险 1.7%[95%置信区间（CI）1.4%-2.1%；N=5180]）。肱骨（42.0%[95%CI 31.8%-52.6%；n=39]）和胫骨（28.0%[95%CI 19.1%-38.2%；n=26]）是最常见的应力性骨折部位。病例因骨折而错过训练的中位数为 63 天（四分位距（IQR）49-82）。在诊断后的 12 个月内，病例马的比赛起跑中位数减少了 4 次（IQR 2-4，P<0.0001），比赛收入中位数减少了 206188 港元（IQR 港元 0-436800，P=0.007）。病例和对照组的职业寿命无显著差异（中位数 2 年 3 个月；IQR 15.3-39.1 个月；P=0.2）。
仅纳入了通过 NS 诊断的应力性骨折，因此，本研究不能代表香港所有发生的应力性骨折。
在进入香港的 1 年内发生应力性骨折的赛马在训练、收入和比赛起跑方面损失了大量时间。然而，整体职业寿命并未受到影响。
