Thomason J J
Department of Biomedical Sciences, University of Guelph, Ontario, Canada.
Equine Vet J Suppl. 1998 Sep(26):86-95. doi: 10.1111/j.2042-3306.1998.tb05126.x.
Objectives were to examine the deformation of the healthy equine front hoof during locomotion, by recording strains on its outer surface, and to test whether its mechanical behaviour is significantly altered under different locomotory conditions and variation in hoof shape. Strains were recorded in vivo from 5 rosette gauges around the circumference of the right forehooves of 12 horses. The magnitudes and orientations of principal strains at the midstep were compared statistically for different conditions of shoeing (shod vs. unshod), gait (walk vs. trot), substrate (treadmill vs. ground), and direction of travel (straight, right turn, left turn). Principal strains were regressed on 4 variables describing hoof shape-toe length, toe angle, and medial and lateral wall angle--to describe their contribution to variations in strain and hoof deformation. Shoeing did not essentially change the magnitudes of the larger, compressive principal strain, but caused some strain reorientation. Shoes decreased the variation in strains indicating that they tend to stabilise the deformation of the hoof. Strain magnitudes were significantly greater at trot than walk, but there was little change in orientation indicating that the general pattern of deformation of the hoof is constant between these 2 gaits. Strain patterns showed small but significant differences between locomotion on the treadmill and on ground, with the differences being more apparent at the toe than at the sides of the hoof. When turning, the quarter on the inside of the turn experienced 40% more strain than during straightline motion, while strain was similarly reduced on the opposite quarter. Strain magnitudes increase with toe length and toe angle, but were inversely proportional to medial and lateral angles. The change with toe length correlated with the range of body size of the animals in the sample. The change with toe angle was contrary to that found in in vitro tests. The change with medial and lateral angles indicated that hooves with more upright quarters are stiffer and possibly provide less impact absorption.
目的是通过记录健康马前蹄外表面的应变，来研究其在运动过程中的变形情况，并测试在不同运动条件和蹄形变化下其力学行为是否发生显著改变。在12匹马的右前蹄圆周周围的5个应变片上进行了体内应变记录。对不同的钉蹄条件（钉蹄与未钉蹄）、步态（行走与小跑）、地面（跑步机与地面）和行进方向（直线、右转、左转），比较了步幅中点处主应变的大小和方向。将主应变与描述蹄形的4个变量——蹄尖长度、蹄尖角度以及内侧和外侧壁角度——进行回归分析，以描述它们对应变变化和蹄变形的贡献。钉蹄本质上并没有改变较大的压缩主应变的大小，但导致了一些应变重新定向。蹄铁减少了应变的变化，表明它们倾向于稳定蹄的变形。小跑时的应变大小明显大于行走时，但方向变化很小，表明在这两种步态之间，蹄的总体变形模式是恒定的。应变模式在跑步机上和地面上的运动之间显示出微小但显著的差异，这些差异在蹄尖处比在蹄的两侧更明显。转弯时，转弯内侧的四分之一区域所受应变比直线运动时多40%，而相对的四分之一区域的应变则类似地减少。应变大小随蹄尖长度和蹄尖角度增加，但与内侧和外侧角度成反比。随蹄尖长度的变化与样本中动物的体型范围相关。随蹄尖角度的变化与体外测试的结果相反。随内侧和外侧角度的变化表明，蹄壁更直立的蹄更硬，可能提供的减震效果更差。
