Many of the practices and principals of management for reducing the exposure of dairy cows to environmental mastitis pathogens were introduced a quarter of a century ago22–25 and have been the subject of numerous reviews.1,3,21 The common theme for reducing mastitis pathogens in the cows’ environment is reducing moisture and organic contamination.1 Frequent manure removal, avoiding overstocking of cows, taking precautions to eliminate stagnant water around cows, and providing clean, dry inorganic bedding for cows to lay on are important management considerations. These factors of environmental hygiene transcend stall barns, manure pack barns, open corrals, and pasture systems. The emphasis of control should center on protecting periparturient animals during wet, hot periods of the year when mastitis pathogen growth in the environment is greatest. As the dairy industry in North America changes and progresses to adapt to economic, social, and environmental demands, the old adage of keeping cows cool, dry, and comfortable remains paramount in managing environmental mastitis.