Heat stress in livestock trailers during summer transport is a major welfare problem causing illness and death, requiring both equipment standards and management changes to protect animal welfare during transport.
Livestock transport during summer heat represents one of the most acute welfare emergencies in farming, combining physical confinement with thermal stress in animals with limited ability to thermoregulate. Pigs are particularly vulnerable: they cannot sweat effectively, have high metabolic heat output from social crowding, and are often transported at stocking densities that further restrict air circulation. The welfare solution requires both equipment standards — mandatory forced ventilation on trailers above a certain capacity — and management changes including scheduling transport during cooler hours, reducing stocking density in hot weather, and providing water misting. Some countries have begun imposing transport restrictions during heatwaves; welfare-centered policy should make such restrictions standard rather than exceptional.