Short communication: Risk factors for sonographically detectable udder edema in overbagged cows at dairy shows

At dairy cow shows, the appearance of the udder is very important. To show cows at their best, udders are often presented in an overbagged state by extending milking intervals before the show. This practice represents an animal welfare issue because it is associated with behavior changes (e.g., excessive abduction and decreased eating time) and may affect the health of the animal. The aim of the current study was to determine the association between various parameters (e.g., milk yield, days in milk, milking procedures, or administration of nonsteroidal anti-inflammatory drugs, steroids, or diuretics) and the sonographically detectable udder edema score. Data were collected from the show catalogs, by interviewing the exhibitors, by analyzing official veterinary treatment protocols and official milking data, via laboratory analysis of blood samples, and by sonographic examinations of the udders at the show. For sonographically detectable udder edema scoring, 3 scans were taken, 1 on each fore quarter and 1 incorporating both rear quarters at the level of the median suspensory ligament. For grading the scans, a scoring system of 4 grades (score 0 = no edema, 1 = slight edema, 2 = moderate edema, 3 = severe edema) was used. Data from 321 cows of different breeds were collected at 4 highly competitive Swiss dairy shows (shows A-D) between January and September 2017. To determine risk factors for sonographically detectable udder edema, data were analyzed with 2 different logistic regression models. In model 1, the odds ratios were 3.33 (milking intervals of ≥16 h vs. <14 h), 3.84 (show A vs. show C), and 7.39 (dairy breeds vs. dual-purpose breeds). Milking intervals of dairy breeds were significantly higher than those of dual-purpose breeds. In model 2, milking interval was the only significant risk factor with an odds ratio of 9.00 for milking intervals of ≥16 h. Only the milking intervals represented a relevant risk factor in both models; therefore, we concluded that the previously described sonographic udder edema scoring is a useful technique for detecting overbagged udders at dairy shows. Its routine implementation may improve cow welfare at dairy shows.