Racing performance of juvenile Thoroughbreds with femoropatellar osteochondrosis at auction: A retrospective case‐control study

Background Osteochondrosis dissecans (OCD) is common in the femoropatellar joint in Thoroughbred yearlings for sale at auction and there is no consensus on the effect on racing outcomes. Objectives Describe femoropatellar OCD in juvenile Thoroughbreds and compare the racing performance of affected Thoroughbred horses to siblings and unaffected horses from the same sale. Study design Retrospective case–control study of juvenile horses born 2010–2016. Methods Radiographic reports from 27 Thoroughbred auctions of weanling (5–11 months of age) and yearling (12–22 months of age) horses were reviewed to identify femoropatellar OCD. Age and sex of cases and controls were obtained from the sales catalogue. Racing performance was obtained from an online database. Correlation between lesion characteristics and racing performance were assessed using Pearson and Spearman correlations for continuous and ordinal/categorical variables respectively. Racing performance was compared between cases and sibling controls and age‐ and sex‐matched sale number controls from the same sale with Poisson distribution and log link. Significance level of alpha = 0.05 was used. Results Femoropatellar OCD was identified in 429 horses with North American race records. OCD was present on 519 lateral trochlear ridges and 54 medial trochlear ridges. There were more males in the case group (70%) than in the sibling control group (47%). Case racing performance was compared to 1042 sibling and 757 hip controls. There were significant but small decreases in racing metrics of cases and increases in males for years raced, total starts, starts for 2–5 years of age, total placings, and placings at 2–4 years of age. Analysis of specific lesion metrics revealed weak correlations for performance outcomes (positive and negative) resulting in an inability to draw firm conclusions. Main limitations Retrospective study where case management was unknown. Conclusions Femoropatellar OCD in juvenile Thoroughbreds for sale at auction decreases some racing outcomes. 总结 背景 在纯血马周岁拍卖会的中，股髌关节骨软骨分离症(OCD)很常见，其对比赛结果的影响尚无共识。 目的 描述幼年纯血马的股髌关节骨软骨分离症，并将有病症的纯血马与其兄弟姐妹马匹和同一场拍卖会无病症的马匹的比赛表现进行比较。 研究设计 对2010‐2016年出生的幼马进行回顾性病例对照研究。 方法 回顾27场纯血马拍卖会的马匹X线影像报告，分别是断奶驹(5–11个月)和周岁驹(12–22个月)，确定股髌关节骨软骨分离症。病例组和对照组马匹的年龄和性别从拍卖销售目录中获得。出赛成绩从在线数据库中取得。病变特征与赛马表现之间的相关性分别采用Pearson和Spearman法，对连续变量和顺序/分类变量进行评估。用泊松分布和对数连接比较病例组和其兄弟姐妹对照组以及来自同一批次拍卖的年龄和性别匹配臀部对照组的赛马表现。显著性水平α = 0.05。 结果 在北美比赛记录中，429匹的马发现了股髌关节骨软骨分离症(OCD)。OCD存在于519个外侧滑车(LTR)和54个内侧滑车(MTR)。病例组的公马(7