Pigs are highly susceptible to heat stress because they cannot sweat and have limited thermoregulatory capacity. As global temperatures rise, heat stress is an increasingly serious welfare challenge for intensively farmed pigs.
Heat stress in pigs causes measurable physiological and psychological suffering. Animals experiencing thermal overload show open-mouth breathing, lateral lying, increased aggression, and in extremes, convulsions and death. The inability to wallow — a primary natural thermoregulatory behaviour — means intensive systems must provide mechanical cooling or risk significant welfare failures. As climate change drives more frequent extreme heat events, this is a growing problem. Farms without adequate cooling infrastructure expose pigs to preventable suffering during summer peaks. Transport during hot weather without temperature management is particularly dangerous and causes a proportion of the annual dead-on-arrival figures in pigs.