Effect of analgesia during hoof trimming on gait, weight distribution, and activity of dairy cattle.

Sixty-six lactating cows were either injected with flunixin meglumine (2.2mg/kg of BW) immediately before hoof trimming (n=28), injected with a saline solution immediately before hoof trimming (n=28), or injected with a saline solution immediately before sham hoof trimming (control; n=10). Gait scores, time spent lying down, frequency of steps, and how cows distributed their weight among their legs when standing before, during, and after injections were measured to assess whether automated measures of activity and weight distribution can detect lameness and the effects of pain mitigation during hoof trimming. The overall gait score was positively correlated with the variability of the weight applied the rear legs (r=0.32) and negatively correlated with the rear leg weight ratio (LWR; r=-0.52) and the frequency of steps (r=-0.43). The rear LWR was the best predictor of cows being lame (NRS >3), accounting for 27% of the variation in the likelihood of a cow being lame and 11% of the variation in the likelihood of a cow having an infectious hoof lesion. For each 5% increase in the rear LWR, the likelihood of being lame decreased by 30% (odds ratio = 0.71; 95% confidence interval = 0.56, 0.90) and the likelihood of being afflicted with an infectious hoof disease decreased by 20% (odds ratio = 0.81; 95% confidence interval = 0.67, 0.98). Neither hoof trimming nor a combination of hoof trimming and analgesia significantly affected gait score or any measure of weight distribution. Daily lying time increased during the 2 d following hoof trimming independently of the flunixin meglumine injection. However, this increase was not sustained for longer than 2 d when cows were injected with flunixin meglumine. Measures of weight shifting between legs while cows are standing and measures of activity show great potential as automated methods of detecting lameness and may also provide a tool for future evaluation of lameness therapies, such as hoof trimming and pain mitigation. Copyright (c) 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.