INRA, UMR Bioagress Epidemiol & Anal Risque 1300, F-44307 Nantes, France.
Prev Vet Med. 2011 Aug 1;101(1-2):96-106. doi: 10.1016/j.prevetmed.2011.05.009. Epub 2011 Jun 12.
Developmental Orthopaedic Disease (DOD) in limb joints is frequent, can cause lameness and is a major cause of economic losses for the horse breeding industry. Studies on risk factors for DOD usually dichotomise the outcome to presence/absence without considering the extent of the disease, which can be appreciated by the number or the severity of the lesions. The aim of this study was to assess the effects of growth, exercise conditions and feeding practices on the number of radiographic findings (RF) of DOD in a cohort of horses, assuming that the risk factors associated with the presence of the disease and the number of RF may differ. We recruited broodmares on 21 stud farms in the Normandy region, France in 2002-2004. The stud farms were visited regularly to collect growth, exercise conditions, and feeding practices data from the end of the gestation to the weaning of the foal. The carpus, the front and hind digits, the tarsus and the stifle of the foals were radiographed at approximately six months of age. Each foal was classified according to the absence (no RF) or presence (≥1 RF) of DOD and to the number of RF. A zero-inflated Poisson model was used to simultaneously determine risk factors for presence/absence and for the number of RF of the disease. The convenience sample consisted of 378 foals, 53.1% of which did not have any RF. The mean number of RF per foal was 1.25 and the variance was 2.80. Comparing to the Poisson, negative binomial, and zero-inflated negative binomial regressions, the zero-inflated Poisson model was found to be best suited for these data. Of the 295 foals with complete data, three risk factors were significantly associated with a higher risk of being affected by DOD: high wither height increase, large group size in pasture and large pasture size. Seven risk factors were associated with the number of RF: wither height at 30 days of age, age of the mare, breed, regularity of exercise, Ca/P level in the mare and foal rations, group size in pasture, and the type and frequency of handling. This study shows that risk factors vary for the presence and extent of DOD, and that the use of a count model achieves a more detailed determination of risk factors for the presence of DOD and for the number of RF of DOD compared to the more conventional dichotomy presence/absence of the disease.
发育性骨科疾病（DOD）在肢体关节中很常见，可导致跛行，是马养殖业经济损失的主要原因。DOD 风险因素的研究通常将结果分为存在/不存在，而不考虑疾病的严重程度，这可以通过病变的数量或严重程度来评估。本研究旨在评估生长、运动条件和饲养实践对队列中马匹 DOD 的放射学发现（RF）数量的影响，假设与疾病存在和 RF 数量相关的危险因素可能不同。我们于 2002 年至 2004 年在法国诺曼底地区的 21 个种马场招募了母马。定期访问种马场，从妊娠结束到驹子断奶，收集生长、运动条件和饲养实践数据。大约在六个月大时，对驹子的腕关节、前肢和后肢的指骨、跗关节和膝关节进行 X 光检查。根据 DOD 的存在（无 RF）或不存在（无 RF）以及 RF 的数量，将每只驹子分为两类。使用零膨胀泊松模型同时确定疾病存在/不存在和 RF 数量的危险因素。方便样本包括 378 匹马驹，其中 53.1%没有任何 RF。每匹马驹的平均 RF 数量为 1.25，方差为 2.80。与泊松、负二项和零膨胀负二项回归相比，零膨胀泊松模型最适合这些数据。在 295 只具有完整数据的驹子中，有三个危险因素与患 DOD 的风险较高显著相关：肩高增加、牧场中大群规模和大牧场面积。七个危险因素与 RF 数量有关：30 天龄时的肩高、母马年龄、品种、运动规律、母马和驹子日粮中的 Ca/P 水平、牧场中的群规模以及处理的类型和频率。本研究表明，DOD 的存在和严重程度的危险因素不同，与更传统的疾病存在/不存在二分法相比，使用计数模型可以更详细地确定 DOD 的存在和 DOD 的 RF 数量的危险因素。
