Fig. 1

Distribution of selected udder pathogens in milk samples from Norwegian dairy cows between 2000 and 2020. Summary of bacterial findings reported by the national mastitis laboratories (TINE Mastitis Laboratory and the Norwegian Veterinary Institute until 2018) to the Norwegian dairy herd recording system between 2000 and 2020 [6]. Number of sampling events (sets of quarter milk samples) per year ranged from 6563–18,044. Data are presented as the percentage of cows receiving the diagnosis in at least one quarter, meaning that each cow can have up to four diagnoses per sampling event. The marked increase of non-aureus staphylococci (NAS) after 2005 is explained by altered diagnostic criteria for defining an intramammary infection caused by NAS