Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Paroninkuja 20, 04920 Saarentaus, Finland.
Department of Production Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Paroninkuja 20, 04920 Saarentaus, Finland; Department of Agricultural Sciences, University of Helsinki, PL 27, 00014 Helsinki, Finland.
J Dairy Sci. 2021 Aug;104(8):9173-9184. doi: 10.3168/jds.2020-19731. Epub 2021 May 21.
Digital dermatitis (DD) is a severe bacterial hoof disease found worldwide. The disease can be classified into 5 different stages, denoted as M1 to M4 and M4.1, by clinical examination. The main objective of this study was to estimate prevalence of DD lesions in Finnish freestall dairy cattle population through hind feet inspection of standing cows with a mirror. Another aim was to estimate the sensitivity and specificity of mirror scoring on standing cows in a pen or in a milking parlor without washing the feet. Three veterinarians visited 81 randomly selected herds across the country. During the herd visits, hind feet of standing cows (n = 7,010) were scored with a mirror without washing the feet, either when the cows were standing in a pen (n = 4,992) or in the milking parlor (n = 2018). In total, 128 cows (111 from pen and 17 from milking parlor) including 256 feet were chosen with cross-sectional sampling and scored in a trimming chute. Animal-level sensitivity for scoring M2 lesions with a mirror was 55% and specificity was 97%; for all active DD lesions (M1, M2, or M4.1), sensitivity was 36% and specificity was 96%. Sensitivity for scoring any DD lesions was 90% and specificity was 82%. The bias-corrected sensitivity and specificity for scoring any DD lesions were 79% and 92%, respectively. The bias-corrected sensitivity and specificity for scoring M2 DD lesions were 10% and 100%. We found M2 lesions in 12.1% of the study herds, and true herd-level prevalence was the same. Altogether, 33.3% (true prevalence 28.4%) of the herds had either M1, M2, or M4.1 DD lesions. However, only 0.7% (true prevalence 5.4%) of cows in total had active M2 lesions. The within-herd prevalence of M2 lesions (in herds where at least 1 cow had a M2 lesion) was 5.7% and varied between 0.4% and 18.8%. Herds with active DD lesions also had more any DD lesions than herds without active DD lesions. The herd-level prevalence was higher than previously thought, with only 1 herd without any DD lesions. However, the animal-level prevalence of active DD lesions was relatively low. Farmers and veterinarians need to be informed of the disease and possible control measures. Because of the low within-herd prevalence, the control of the disease might be easier than in countries where DD is widespread. Further studies are needed to identify factors associated with DD prevalence in Finnish dairy herds.
数字性皮炎（DD）是一种在世界范围内发现的严重细菌性蹄病。该疾病可通过临床检查分为 5 个不同阶段，分别表示为 M1 至 M4 和 M4.1。本研究的主要目的是通过用镜子检查站立奶牛的后脚来估计芬兰自由放养奶牛群体中 DD 病变的流行率。另一个目的是评估在不洗脚的情况下，在畜栏或挤奶厅站立的奶牛进行镜面评分的敏感性和特异性。三名兽医访问了全国 81 个随机选择的牧场。在牧场访问期间，用镜子对站立奶牛（n = 7010）的后脚进行了评分，既没有洗脚，也没有在畜栏（n = 4992）或挤奶厅（n = 2018）中洗脚。总共使用横断面抽样选择了 128 头奶牛（畜栏中 111 头，挤奶厅中 17 头），并在修剪滑道中进行了评分。使用镜子评分 M2 病变的动物水平敏感性为 55%，特异性为 97%；对于所有活动性 DD 病变（M1、M2 或 M4.1），敏感性为 36%，特异性为 96%。评分任何 DD 病变的敏感性为 90%，特异性为 82%。评分任何 DD 病变的偏倚校正敏感性和特异性分别为 79%和 92%。评分 M2 DD 病变的偏倚校正敏感性和特异性分别为 10%和 100%。我们在 12.1%的研究牧场中发现了 M2 病变，真实的牧场水平流行率相同。总的来说，33.3%（真实流行率 28.4%）的牧场有 M1、M2 或 M4.1 DD 病变。然而，只有 0.7%（真实流行率 5.4%）的奶牛总共有活动性 M2 病变。M2 病变的牧场内流行率（至少有 1 头奶牛有 M2 病变的牧场）为 5.7%，变化范围为 0.4%至 18.8%。有活动性 DD 病变的牧场的任何 DD 病变数量也多于没有活动性 DD 病变的牧场。牧场水平的流行率高于此前的预期，只有 1 个牧场没有任何 DD 病变。然而，活跃 DD 病变的动物水平流行率相对较低。农民和兽医需要了解该疾病和可能的控制措施。由于牧场内的流行率较低，因此与 DD 广泛流行的国家相比，该疾病的控制可能更容易。需要进一步研究以确定与芬兰奶牛场 DD 流行率相关的因素。
