Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California - Davis, Davis, California, USA.
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, California, USA.
Equine Vet J. 2023 Sep;55(5):820-830. doi: 10.1111/evj.13879. Epub 2022 Oct 24.
Equine recurrent uveitis (ERU) is the leading cause of blindness for horses; previous research implicated the leopard complex spotting allele (LP) as a genetic risk factor for insidious uveitis in the Appaloosa. There is limited information about risk in the Knabstrupper.
To evaluate clinical manifestations, disease frequency and potential risk factors for ERU in Knabstrupper horses.
Cross-sectional study.
Ocular examinations were performed on 116 horses, and based on identified anomalies, horses were classified as suspect, ERU-affected or having no clinical signs. Microagglutination testing (MAT) of serum assessed exposure to Leptospira spp. Clinical signs, age, sex, base colour, coat pattern, LP and PATN1 genotypes, percent white at birth, progressive roaning and Leptospira were assessed as risk factors using multivariable exact logistic regression, accounting for clustering at the barn level. Additionally, a pedigree analysis was performed (n = 20 cases and 21 controls), and coefficients of coancestry (CC) and inbreeding were calculated.
Prevalence of insidious uveitis in this sample of Knabstruppers was 20.7%. Similar to findings for Appaloosas, LP homozygotes had higher odds of uveitis compared with true solid (N/N) horses (LP/LP OR = 7.64, 95% CI [0.8 to +INF], p = 0.04) and age was also identified as a risk factor. After accounting for LP, the 16-20 age group had higher odds compared with the youngest group (OR = 13.36, 95% CI [1.4-213.4], p = 0.009). The distributions of average CC were significantly different between cases and controls (p = 0.01).
A relatively small sample size decreased the power for detecting additional associations. The progressive nature of insidious uveitis may have prevented identification of younger affected horses.
Our data support genotyping for LP to assess risk of ERU in Knabstruppers. Additional studies are necessary to develop more robust risk models across LP breeds for earlier detection and improved clinical management.
马的复发性虹膜炎（ERU）是导致马匹失明的主要原因；先前的研究表明，豹斑复杂斑点等位基因（LP）是阿帕卢萨马隐匿性虹膜炎的遗传风险因素。关于克纳布斯特鲁珀的信息有限。
评估克纳布斯特鲁珀马 ERU 的临床表现、疾病频率和潜在风险因素。
横断面研究。
对 116 匹马进行眼部检查，并根据发现的异常将马匹分为疑似、ERU 受影响或无临床症状。使用微量凝集试验（MAT）检测血清中钩端螺旋体属的暴露情况。使用多变量精确逻辑回归评估临床症状、年龄、性别、基础色、毛色图案、LP 和 PATN1 基因型、出生时的白色百分比、进行性斑驳和钩端螺旋体作为风险因素，同时考虑到马厩水平的聚类。此外，还进行了系谱分析（n=20 例和 21 例对照），并计算了同源系数（CC）和近交系数。
在这个克纳布斯特鲁珀样本中，隐匿性虹膜炎的患病率为 20.7%。与阿帕卢萨马的发现相似，LP 纯合子患虹膜炎的几率高于真正纯色（N/N）马（LP/LP OR=7.64，95%CI[0.8 至+无穷大]，p=0.04），并且年龄也是一个风险因素。在考虑 LP 后，16-20 岁年龄组与最年轻的年龄组相比，患病的几率更高（OR=13.36，95%CI[1.4-213.4]，p=0.009）。病例组和对照组的平均 CC 分布差异有统计学意义（p=0.01）。
样本量相对较小，降低了检测其他关联的能力。隐匿性虹膜炎的进行性可能阻止了年轻受影响马匹的识别。
我们的数据支持 LP 基因分型，以评估克纳布斯特鲁珀 ERU 的风险。需要进一步研究以在 LP 品种中开发更强大的风险模型，以便更早地发现并改善临床管理。
