Pigs are particularly vulnerable to heat stress due to their limited sweating capacity, and rising summer temperatures under climate change are increasing welfare risks for both indoor and outdoor pigs.
Heat stress causes acute suffering in pigs through hyperthermia, cardiovascular strain, and the inability to cool effectively. Severe heat stress causes death in finishing pigs and heavy sows at temperatures increasingly common in UK and European summers. Outdoor pigs without access to shade or wallowing facilities experience preventable suffering during heat waves. Indoor systems with inadequate ventilation accumulate heat, causing welfare emergencies. Proactive summer management including additional water provision, reduced stocking density in hot periods, and emergency cooling capacity is increasingly necessary as climate change extends hot weather periods.