Interobserver agreement of digital dermatitis M-scores for photographs of the hind feet of standing dairy cattle

摘要

Digital dermatitis (DD) is the leading infectiouscause of lameness in dairy cattle, and it affects theirwelfare and productivity worldwide. At the herd level,DD is often assessed while cows are standing in a milkingparlor, and lesions are most commonly evaluatedusing the M-score. The objective of this study was toexamine the interobserver agreement for M-scores ofthe feet of standing cattle, based on digital color photographsof dairy cattle hind feet. A total of 88 photographsand written descriptors of the M-score were sentto 11 scorers working at 10 different institutions in 5countries. The scorers received no formal training immediatelybefore scoring the photographs; however, allregularly used the M-score to score DD. The answersfor 36 photographs were excluded from the analysis becausethe photograph either had more than 1 M-stageas mode or not all scorers assigned an M-score to it.The M-scores of the 11 scorers from 52 photographswere available for analysis. Interobserver agreementwas tested using Gwet’s agreement coefficient (AC1)and the mode was assumed correct. Overall, moderateagreement emerged for the M-score (AC1 = 0.48).For the individual M-stages, almost perfect agreementexisted for M0 (AC1 = 0.99), M1 (AC1 = 0.92), andM3 (AC1 = 0.82), and substantial agreement for M2(AC1 = 0.61), M4 (AC1 = 0.65), and M4.1 (AC1 =0.71). This outcome indicates the degree of individualvariation in M-scoring in this context by unstandardized,experienced European observers, particularly forthe M2, M4, and M4.1 stages. Standardized training islikely to improve the consistency of M-scoring and thusthe generalizability of future DD research results onthis important endemic disease.