The Lameness of Gait Scoring: Identifying Claw Lesions in Dairy Cattle

Lameness can be defined as a deviation in gait resulting from pain or discomfort from claw or leg injuries. Besides a significant economic, health and welfare problem, lameness is an important reason for culling. Therefore, claw health and lameness are among the major health issues in the dairy industry. It is crucial for veterinarians and producers to focus on both prevention and treatment of lame cows at the same time. Gait scoring systems have proven to be reliable and practical methods that effectively identify lame cows. As it is assumed, but not proven that lameness relates to the occurrence of claw lesions, the aim of this study was to evaluate the use of gait scoring as a tool to identify cows with claw lesions. \n As part of the Lameness and Longevity project of Alberta, fifty-four representative free-stall dairy farms in Alberta were visited. The collected data includes video recordings to assess gait score done by trained observers on a sub-sample of 40 cows from each herd. Asymmetric steps, limping and head bob were the three attributes of the gait to be recorded. The presence of claw lesions on each farm was determined by one of the seven trained hoof trimmers using an automated recording system (Hoof Supervisor®) as part of the Alberta Dairy Hoof Health Project. Gait scores were recorded within 4 weeks of the hoof trimmer’s scheduled visit to allow correlation analysis between gait score and claw lesions. Association was analyzed using Chi-square statistics and sensitivity and specificity were calculated to demonstrate the ability of gait score to identify cows with claw lesions. \nIn our data set of 570 cows from 31 different farms, 49%, 27.5%, 13% and 10.5% of the cows were scored sound, asymmetric, limping and head bob. Twelve different type of lesions where found in the cows originating from all four categories, where digital dermatitis was the most prevalent claw lesion (40%), followed by sole ulcer (14%), white line lesion (14%) and sole haemorrhage (11%). A key finding from our study was that when the claws from a representative proportion of cows in a herd with varying severities of locomotion score were examined, only some of the many lesions observed were linked with increasing lameness (71%). The lack of association between certain lesions and poor gait scores indicates either that these lesions are causing different severities of lameness or that other causes, like leg injuries, are responsible for lameness. \nTo conclude, locomotion score may not be sensitive enough for veterinarians and producers to detect all lesions and therefore, additional tools to detect claw lesions in dairy cows are necessary.