Impact of milking and management practices on the prevalence of bovine mastitis in Brazilian dairy herds

Bovine mastitis remains one of the most economically significant diseases affecting dairy production worldwide, particularly in small- and medium-scale systems. This cross-sectional study evaluated the association between milking hygiene and management practices and the prevalence of clinical and subclinical mastitis in dairy cows from Southern and Southeastern Brazil. Data were collected from 400 lactating cows across 12 dairy farms between November 2024 and July 2025. Clinical mastitis was identified through clinical examination and strip cup testing, while subclinical mastitis was assessed using the California Mastitis Test (CMT), considering scores ≥1+ as positive. The outcome variable was cow-level mastitis status (presence of clinical and/or subclinical mastitis). Descriptive analyses, bivariate tests, and mixed-effects logistic regression models were performed, including farm as a random effect. The overall prevalence of mastitis was 40.5%, with subclinical mastitis predominating (37.3%). Inadequate milking hygiene practices, particularly the absence of combined pre- and post-dipping, were significantly associated with increased odds of mastitis (OR = 0.38; 95% CI: 0.21–0.69). These findings highlight the importance of low-cost preventive practices and reinforce the relevance of management-based interventions for mastitis control in heterogeneous dairy systems. Additionally, the results have implications within a One Health framework by supporting strategies that may reduce antimicrobial use in dairy production.