Pig Heat Stress: A Major Welfare Crisis in Warming Climates

Heat stress is a critical pig welfare problem that causes suffering, reduced production, and death, worsened by climate change and intensive confinement conditions.

Key Facts

Pigs are particularly vulnerable to heat stress because they lack functional sweat glands and cannot pant efficiently
Pigs begin experiencing heat stress at approximately 25 to 27 degrees Celsius, well below temperatures common in summer
Heat stress causes reduced feed intake, elevated cortisol, rapid breathing, lethargy, and prostration
Gestating sows are especially vulnerable, and heat stress during pregnancy causes embryo loss and reduced litter sizes
Climate change is expanding the geographic range and duration of dangerous heat conditions for pig production
High stocking densities in confinement buildings amplify heat load through metabolic heat from animals
Wallowing access dramatically reduces pig body temperature and is a critical behavioral thermoregulation mechanism
Mortality from heat stress in pigs during extreme weather events can be substantial, representing both welfare and production losses

Welfare Considerations

Heat stress in pigs represents widespread, intense suffering that affects hundreds of millions of animals annually worldwide. Pigs in severe heat stress pant heavily, press against cool surfaces, pile on each other to compete for ventilated areas, and may collapse and die. The distress is physiologically comparable to severe heat exhaustion in humans. Pregnant sows experiencing heat stress suffer alongside their embryos, many of which die. Confinement systems that deny pigs wallowing access remove their most effective natural thermoregulation tool. Climate change is rapidly making current housing and management systems inadequate for pig welfare. Urgent action is needed on ventilation, stocking density, outdoor access, and building design to prevent escalating suffering.

What You Can Do

Advocate for mandatory minimum ventilation standards and heat stress action plans in pig farming regulations
Support research into pig housing designs that better manage heat load under changing climatic conditions
Choose pork from farms with outdoor access or documented heat management protocols
Push for climate adaptation plans in agricultural policy to include farmed animal welfare alongside production targets
Support organizations working to improve pig welfare standards globally, including heat stress prevention