Effect of hoof pathologies on subjective assessments of dairy cow gait.

To explore how hoof pathologies affect dairy cattle gait, we studied cows with sole hemorrhages (n = 14), sole ulcers (n = 7), and those with no visible injuries (n = 17). Overall gait assessments, scored from video using a 1 to 5 numerical rating system (1 = sound, 5 = severely lame) and a continuous 100-unit visual analog scale, found cows having sole ulcers had poorer gait than healthy cows (mean +/- SEM: 4.0 +/- 0.13 vs. 3.1 +/- 0.08, and 59 +/- 3 vs. 46 +/- 2, respectively). Six gait attributes (back arch, head bob, tracking-up, joint flexion, asymmetric gait, and reluctance to bear weight) were also assessed using continuous 100-unit scales. Compared with healthy cows, those having sole ulcers walked with a more pronounced back arch (12 +/- 3 vs. 28 +/- 4), more jerky head movement (2 +/- 2 vs. 10 +/- 3), shortened strides (7 +/- 2 vs. 26 +/- 4), and more uneven weighting among the limbs (16 +/- 2 vs. 32 +/- 3). Of all measures, the numerical rating system most effectively discriminated healthy cows from those with sole ulcers (R2 = 0.73), classifying 92% of animals correctly. No differences were detected among cows with and without sole hemorrhages. Intra- and interobserver reliabilities were reasonable for all measures (R2 > or = 0.64) except joint flexion and asymmetric gait. In summary, subjective assessments of dairy cattle gait provide valid and reliable approaches to identifying cattle with sole ulcers.