The Impact of Climate-Driven Heat Stress on Bovine Mastitis: A Review of the Po Valley Dairy System

This review examines the relationship between climate-driven heat stress (HS) and bovine mastitis in the Po Valley, a key European dairy region characterized by intensive production systems and increasing climatic vulnerability. It aims to contextualize how rising temperature–humidity index (THI) levels influence animal health and productivity. This study synthesizes the current literature on biometeorological conditions, epidemiological trends, and physiological mechanisms linking HS to mastitis. Evidence indicates that prolonged exposure to elevated THI impairs thermoregulation, disrupts endocrine and metabolic balance, and weakens immune function, thereby increasing susceptibility to intramammary infections. Epidemiological data reveal a clear seasonal pattern, with mastitis incidence peaking during summer months and a growing predominance of environmental pathogens. Additionally, HS negatively affects milk yield and quality, amplifying economic losses in dairy systems. The findings highlight that mastitis in this context is not merely an infectious disease but a multifactorial condition shaped by environmental, physiological, and management factors. Overall, this review underscores the need for integrated mitigation strategies, including improved housing, nutrition, genetic selection, and precision monitoring, to enhance resilience. In the face of ongoing climate change, adapting dairy production systems will be essential to safeguard animal welfare, maintain productivity, and ensure the long-term sustainability of the Po Valley dairy sector.