Pigs lack functional sweat glands and are highly vulnerable to heat stress in summer, with intensive housing systems often providing inadequate cooling.
Heat-stressed pigs huddle by water sources, pant heavily and show reduced activity and increased aggression — all indicators of significant welfare impact. In finishing pigs, heat stress reduces growth rates and increases mortality risk. In breeding sows, heat stress suppresses fertility and increases embryo loss. Providing adequate wallowing for outdoor pigs and effective ventilation for indoor pigs — temperature sensors, fan triggers, evaporative cooling — are welfare investments with clear production benefits.