Heat stress is one of the most widespread and economically significant welfare problems in dairy farming globally. Climate change is making it worse, demanding urgent management improvements.
Heat-stressed dairy cows experience significant suffering — they are unable to regulate body temperature effectively, leading to panting, reduced resting, crowding near water sources, and immune suppression that increases disease susceptibility. Metabolic heat production from high milk yield creates a welfare paradox: the highest-producing cows suffer most from heat. Reproductive failure during heat stress causes delayed calving and extended periods without pregnancy that affect herd management and individual cow welfare. The welfare intervention is clear: cooling infrastructure including shade, fans, and water sprinklers dramatically reduces heat stress indicators at relatively low cost. However, adoption remains inconsistent globally, particularly in lower-income dairy regions where infrastructure investment is challenging. Climate-adapted breeds and reduced yield targets also merit consideration as long-term adaptation strategies.