Heatwaves cause acute and chronic welfare harm to farm animals through heat stress, reduced productivity, and in severe cases, mass mortality events in poorly ventilated housing.
Livestock heat stress is both a chronic welfare problem that silently reduces animal welfare and productivity across the summer season, and an acute emergency when extreme temperatures combine with poor housing ventilation to cause mass mortality. The physiological experience of chronic heat stress — elevated cortisol, reduced appetite, compromised immune function — represents genuine suffering in sensitive species. Acute heatwave events in poorly ventilated poultry houses can kill thousands of birds through hyperthermia within hours. The mitigation tools are well-understood: shade, evaporative cooling, ventilation, and water. The barrier is primarily economic — capital investment in heat mitigation requires prioritisation of animal welfare over short-term cost minimisation.