Bovine mastitis in a small-scale dairy herd: microbiological diagnosis, antimicrobial susceptibility, and strategic analysis

Mastitis is an inflammatory condition of the mammary gland and a major cause of economic loss in dairy herds, affecting milk yield, quality, and animal welfare. This study was conducted in a Holstein herd in Aguascalientes, Mexico, to identify key bacterial pathogens, assess antimicrobial susceptibility, and evaluate milking practices using a Strengths, Weaknesses, Opportunities, and Threats and Analytic Hierarchy Process (SWOT–AHP) framework. Seasonal sampling was performed during the dry and rainy periods, with 129 milk samples and 66 equipment swabs collected. A higher proportion of bacteriologically positive milk samples was recorded in the rainy season (44 %) compared to the dry season (16 %). Coagulase-negative staphylococcus was the most frequently isolated microorganism, identified in both milk and surfaces. Mixed infections and environmental contamination were more prevalent during the rainy season. Antimicrobial susceptibility testing revealed a significant decline in sensitivity to penicillin, ampicillin, erythromycin, and tetracycline during the rainy season, while resistance to oxacillin remained consistently high. The SWOT-AHP analysis identified twelve strategic factors, with the highest global priorities assigned to the owner’s technical training (0.101), seasonal mastitis risk (0.101), and the potential for genetic improvement (0.101). Additional relevant factors included staff workload and hygiene challenges. The integration of microbiological data with strategic analysis provided a practical decision-making framework tailored to small-scale dairy operations. These findings underscore the value of continuous monitoring, rational antimicrobial use, and context-specific hygiene strategies. The combined application of qualitative diagnostics and semiquantitative scoring offers a replicable model for improving udder health and sustainability in tropical dairy production systems.