Retrospective study of the correlation between hygiene score and the prevalence of papillomatous digital dermatitis in dairy cows

In this retrospective study the recorded data from 75 dairies 2932 cows with papillomatous digital dermatitis “PDD” were considered and a simple scoring system for assessing cow cleanliness was used to determine whether hygiene scores were correlated with individual PDD cow. Screening cows at the parlor by using a water hose method and verification the case following inspecting restrained cows in a chute were the procedure for case selection and estimation of the prevalence of PDD in each herd. A cow hygiene scoring system was developed by modifying the cleanliness scoring system developed by Chiappini et al. Cleanliness was scored in 5 body areas، tail head، lateral aspect of the thighs، ventral aspects of the abdomen، udder and lower portion of the hind limbs on scale from 1 to 5 were 1 indicated that the area was very clean and 5 indicated that the area was very dirty. For evaluating of repeatability، accuracy and ease of use 3 experts used the hygiene scores for each of the 5 body areas assigned to each of 2932 cows and the correlation coefficient was calculated to determine whether hygiene scores were correlated with the prevalence rate of PDD in 75 dairies. The regression model was used with herd prevalence as dependent variable and hygiene scores as independent variable and the values of P≤0. 05 were considered significant. Mean correlation coefficient for hygiene scores assigned by the 3 evaluators was 0. 924. Hygiene scores for tail head، lateral aspect of the thigh، ventral aspect of the abdomen and udder were not significantly correlated with PDD prevalence rate and lower portion of the hind limbs and udder-hind limb composite scores were significantly associated with PDD prevalence، with PDD increasing as scores increased. Results suggest the hygiene scoring system was repeatable، accurate and easy to use. However only hygiene scores for the lower portion of the hind limbs were significantly associated with PDD prevalence in herd level.