Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe J2S 2M2, Canada.
Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint Hyacinthe J2S 2M2, Canada.
J Dairy Sci. 2020 Jul;103(7):6412-6421. doi: 10.3168/jds.2019-17250. Epub 2020 Apr 29.
Sole ulcers are reportedly one of the most prevalent diseases associated with lameness in dairy cattle, significantly affecting animal welfare and farm profitability. The degree to which sole soft tissues, healthy or ulcerated, are able to maintain their structure and function when subjected to compressive forces remains unknown. Therefore, the aims of the present study were to assess sole tissue biomechanics in healthy and ulcerated claws and to describe correlated histology. Cylindrical samples were harvested from zones 4 and 6, as described by the international foot map, from hind lateral healthy (n = 12) and ulcerated bovine claws (n = 8; animals n = 12). Tissue biomechanics and morphology were evaluated via compressive tests and hematoxylin-eosin-phloxine-saffron staining, respectively. A 2-sample t-test was used to compare zones' mechanical properties between healthy and ulcerated tissues, and the Cochran-Mantel-Haenszel test was used to measure the effect of claw zone on histology. The fibril modulus (E) and permeability (k) respectively increased and decreased in ulcerated claws (E = 0.201 ± 0.104 MPa; k = 0.128 ± 0.069 mm/MPa·s) compared with healthy claws (E = 0.105 ± 0.050 MPa; k = 0.452 ± 0.365 mm/MPa·s) only for zone 6. Histology scores equal to or greater than 3 were associated with macroscopic presence of ulceration. A higher proportion of adipose tissue (30% or more) was associated with zone 6 compared with zone 4, but no difference was seen between healthy and ulcerated claws. Ulcerated claws had a higher prevalence of exostoses compared with healthy ones (33% vs. 8%). Sole soft tissues showed, as hypothesized, a viscoelastic behavior using unconfined compression testing, which, however, may not reflect in vivo loading conditions. Clinical and histological signs of sole ulceration were not associated with decreased strength of the supportive apparatus of the distal phalanx in zone 4 in this study.
据报道，蹄底溃疡是奶牛跛行中最常见的疾病之一，严重影响动物福利和农场盈利能力。在受到压缩力的情况下，健康或溃疡的蹄底软组织能够保持其结构和功能的程度尚不清楚。因此，本研究的目的是评估健康和溃疡蹄爪的蹄底组织生物力学，并描述相关的组织学。根据国际蹄映射，从第 4 区和第 6 区采集圆柱形样本，来自后外侧健康（n = 12）和溃疡牛蹄（n = 8；动物 n = 12）。通过压缩试验评估组织生物力学和形态，分别通过苏木精-伊红-派洛宁-藏红花染色。使用两样本 t 检验比较健康和溃疡组织的区域机械性能，使用 Cochran-Mantel-Haenszel 检验测量爪区对组织学的影响。与健康蹄相比，溃疡蹄的纤维模量（E）和渗透性（k）分别增加和降低（E = 0.201 ± 0.104 MPa；k = 0.128 ± 0.069 mm/MPa·s），仅第 6 区如此（E = 0.105 ± 0.050 MPa；k = 0.452 ± 0.365 mm/MPa·s）。组织学评分等于或大于 3 与肉眼可见的溃疡存在相关。与第 4 区相比，第 6 区的脂肪组织（30%或更多）比例更高，但健康和溃疡蹄之间没有差异。与健康蹄相比，溃疡蹄的骨赘发生率更高（33%比 8%）。正如假设的那样，使用无约束压缩试验，蹄底软组织表现出粘弹性行为，但这可能无法反映体内的加载条件。在本研究中，临床和组织学的蹄底溃疡迹象与第 4 区远指骨支撑装置的强度降低无关。
