Pig Heat Stress: Recognition and Prevention on Farms

Heat stress is a serious welfare and production challenge in pig farming, as pigs lack the ability to sweat effectively and are highly susceptible to heat-related illness in warm conditions.

Key Facts

Pigs begin to show signs of heat stress above 25C, with severe distress and mortality risk above 35C
Pigs cannot sweat effectively and rely on panting and wallowing for thermoregulation
Signs of heat stress include open-mouth breathing, lethargy, reduced feed intake, and piling behavior
Pregnant sows are particularly vulnerable to heat stress, which increases stillbirth rates and reduces litter size
Ventilation systems in indoor pig housing must be designed to maintain thermal comfort in peak summer temperatures
Access to water is critical during hot periods; water intake can double during heat stress events

Welfare Considerations

Heat stress causes significant suffering in pigs, progressing from discomfort and behavioral distress to hyperthermia and death in severe cases. Pregnant sows experiencing heat stress face reproductive failure on top of thermal suffering. Climate change is increasing the frequency and severity of heat stress events across pig-producing regions. Inadequate ventilation in indoor housing represents a preventable welfare failure. Provision of cooling measures including wet mud wallows for outdoor pigs and effective ventilation for indoor pigs is a basic welfare requirement.

What You Can Do

Ensure indoor pig housing has ventilation systems rated for peak summer temperature management
Provide adequate clean water access with sufficient flow rate to meet increased demand during hot periods
Provide outdoor pigs with mud wallows and shade during warm weather periods
Monitor pigs more frequently during heat events and be prepared to intervene if distress signs appear
Advocate for housing standards that require thermal comfort assessment across all climate scenarios