Mastitis - inflammation of the udder - is the most common and costly disease of dairy cows. It causes significant pain and is a leading indicator of welfare problems in dairy herds.
Mastitis is both a significant welfare problem and an indicator of herd management quality. High mastitis rates reflect crowding, hygiene failures, nutritional stress, and inadequate post-milking teat disinfection. Clinical mastitis causes acute pain from udder inflammation - cows with mastitis show pain behaviours including reduced lying time, licking the affected quarter, and reluctance to be milked. Subclinical mastitis causes chronic low-grade suffering. Effective mastitis prevention through housing design, nutrition, milking hygiene, and prompt treatment reduces both the welfare cost to individual cows and antibiotic use.