The development of a reliable 5-point gait scoring system for use in dairy goats

Numerical rating scales are frequently used in gait scoring systems to detect lameness in dairy animals. The gait scoring systems commonly used in dairy goats are based on 4-point scales that focus on detecting and judging the severity of a definite limp. An uneven gait, such as a shortened stride or not ‘tracking up’, is arguably the precursor to the development of a limp, and thus identifying such changes in gait prior to a limp developing could provide opportunity for early treatment. The aims of this study were to develop a 5-point gait scoring system that included an uneven gait category, and to determine whether it could reliably be used to assess lameness in dairy goats. Forty-eight Saanen cross 2 and 3 year old lactating does were enrolled from a commercial dairy goat farm. Two observers carried out weekly lameness assessments for a period of 7 wk using a 5-point scoring system. Additionally to wk 1 being lived scored, the goats were also video recorded. This allowed wk 1 to be rescored using the developed 5-point system and the previously used 4-point system, and comparisons of score distributions to be made. Using the 4-point system, 81% of the goats were assigned score 1 (normal gait), using the 5-point system 36% of the goats were assigned a score 1 (normal gait), with 50% assigned a score 2 (uneven gait). At Assessment 1, inter-observer reliability was only moderate (κw = 0.54). Therefore Assessment 2 was used as a training session, which improved agreement (κw = 0.90 to 1.00) for the subsequent assessments. At Assessment 1, sensitivity between observers differed most when distinguishing between scores 1 and 2 (77% and 65%, respectively). However, continued scoring and training improved sensitivity (range: 89-100%, 97-100% for score 1 and 2 respectively). This highlights the likely reason existing scoring systems for dairy goats do not include “uneven gait”, as distinguishing it from a normal gait was challenging without training. Overall, a 5-point scoring system was found to be more sensitive to low level lameness than a 4-point system and could be used to reliably assess the gait of dairy goats with observer training, potentially facilitating early detection of lameness.