Mastitis is the most economically costly disease in dairy farming and causes significant welfare harm to millions of cows. Understanding its causes and prevention reveals important intersections between productivity and welfare.
Mastitis causes significant acute suffering in clinical cases, with swollen, painful quarters, systemic fever, and reluctance to walk causing acute welfare compromise. Cows with severe mastitis reduce feed intake, stand in unusual postures to relieve udder pressure, and show social withdrawal. Chronic subclinical mastitis causes persistent discomfort and immune activation without the dramatic signs that attract veterinary attention. The high prevalence of mastitis in intensive dairy systems reflects the intersection of high genetic milk production potential with management conditions that challenge udder health. The Danish experience demonstrates that systematic breeding and management approaches can dramatically reduce mastitis incidence with welfare and economic co-benefits. This makes mastitis reduction one of the most tractable and impactful welfare improvements available to the dairy sector.