Technical note: Evaluation of a sonographic overbagging edema scoring system for show cows: Comparison with visual inspection

Overbagged udders are commonly seen at dairy cow shows due to prolonged milking intervals. The aims of this study were to describe the prevalence of udder edema in dairy cows at shows as determined by sonography and to suggest a sonographic scoring system, which was evaluated for reproducibility and repeatability. At 4 highly competitive Swiss dairy cow shows, 319 cows of various breeds were examined. Sonographic scans—1 from each fore quarter and 1 from the rear, representing both hind quarters—were collected by 3 experienced veterinarians at defined positions predisposed to overbagging edema. Sonographic scans were scored with the aid of a newly suggested scoring system (score 0 = no edema, grade 1 = slight edema, grade 2 = moderate edema, grade 3 = severe edema). Further, 139 video sequences from behind while the cows were walking and the same number of photographs of the udder each from the left, right, and behind were selected. The photographs and video sequences were visually scored for different parameters as 0 = not present or 1 = present except for abduction, which was scored on a visual analog scale (0 = no abduction; 100 = maximal imaginable abduction). Visual scores were then compared with the sonographic scoring (Pearson's chi-squared). The prevalence of udder edema scores 1, 2, and 3 was 14.0, 6.5, and 2.3%, respectively. Interobserver reliability for objective sonographic scoring (κ = 0.815) and intraobserver agreement (κ = 0.90 and 0.85 for 2 different observers) was estimated as “almost perfect.” Interobserver agreements for visual parameters were κ = 0.40 or less except for teat shape (κ = 0.52). Classification of the videos resulted in better interobserver agreement; when rating hind limb abduction, Spearman correlation coefficient was 0.61, whereas κ = 0.61 for absence of udder movement. Udder movement and teat shape were significantly associated with the edema score. The higher inter- and intraobserver reliability of the sonographic edema scoring compared with the visual scoring system indicates that the newly suggested scoring system might be used in the future to objectively identify udder edema in cows at dairy shows.