Overview
Pigs are particularly vulnerable to heat stress because they lack functional sweat glands and cannot pant as effectively as other species. They rely almost entirely on behavioral thermoregulation (wallowing, shade-seeking, reduced activity) and respiratory cooling. This makes them highly susceptible to high temperatures, and as climate change increases frequency and intensity of heat events, heat stress welfare impacts on pigs are growing rapidly in scale and severity.
⚠️ Heat stress occurs in pigs above 20-22°C ambient when housed without cooling
⚠️ Estimated 75% of EU pig farms will experience significant heat stress events annually by 2050
Welfare Impacts of Heat Stress
Heat stress causes a cascade of welfare harms in pigs:
- Hyperthermia: Core temperature above 40°C causes pain, disorientation, and organ damage
- Respiratory distress: Open-mouth breathing, gasping, and panting at high temperatures
- Reduced feed intake: Decreased food consumption causes metabolic disruption and frustration of feeding motivation
- Reproductive failure: Heat stress during gestation causes fetal losses and impairs sow productivity
- Mortality: Heat waves cause mass pig mortality events — thousands of animals dying simultaneously
⚠️ 2022 UK heat wave: estimated 10,000+ pig deaths; similar events in France, Spain, Netherlands
⚠️ Transport during heat stress: mortality risk increases 3-5× above 25°C