Farmed Pig Heat Exchange and Thermoregulation

Pigs cannot sweat and are highly vulnerable to heat stress. Understanding their thermoregulatory biology helps design welfare-positive housing, particularly as climate change increases extreme temperature events.

Key Facts

Pigs have few sweat glands and cannot effectively dissipate heat through sweating like humans
Panting is the primary thermoregulatory mechanism but is energetically costly and inefficient
Wallowing in water or mud is the natural thermoregulatory behaviour - mud evaporation cools the skin efficiently
The upper critical temperature for pigs is approximately 25-27 degrees Celsius, lower for pregnant sows
Heat stress causes reduced feed intake, poor growth, impaired reproduction, and increased mortality
Shade, wallowing opportunities, and evaporative cooling (misting systems) are effective welfare interventions
Stocking density affects temperature in pig buildings - lower density reduces heat load per unit area
Fast-growing breeds and heavily pregnant sows are most vulnerable to heat stress events

Welfare Considerations

Heat stress in pigs causes genuine acute suffering - panting, behavioural desperation to find cool conditions, and in severe cases prostration and death. The pig's inability to sweat makes thermal management a fundamental welfare requirement rather than a comfort consideration. Outdoor systems that deny wallowing opportunities during hot periods cause preventable suffering. Climate change makes investment in heat mitigation infrastructure increasingly urgent for both indoor and outdoor pig systems. Providing adequate shade, wallowing, and ventilation is a minimum welfare obligation during warm conditions.

What You Can Do

Support pig welfare standards requiring shade, wallowing access, and cooling provision in all systems
Advocate for stocking density limits that account for thermal load during extreme heat events
Choose outdoor pork from systems with certified access to wallowing areas and shade
Learn about pig thermoregulation to understand why climate adaptation is urgent for pig welfare