From Longman Dictionary of Contemporary Englishmastitismas‧ti‧tis /mæˈstaɪtɪs/ noun [uncountable] a painful swelling of the breast or udder (=the part of some animals that gives milk)
Examples from the Corpus
mastitis• Geneticists estimated that had they not selected for mastitis resistance the national incidence would have increased by 1.5% over that period.• It has also been shown to increase mastitis and lameness and lower general condition.• These records showed that there were occasional mastitis, lameness and infertility problems which were the main factors in reducing milk production.• The main problem areas were mastitis control, lameness and infertility - not an unknown combination in Britain. 