Porcine respiratory disease complex is the most economically significant disease in pig production. Ventilation quality, stocking density, and biosecurity are the primary welfare and control levers.
Porcine respiratory disease causes significant suffering through difficulty breathing, fever, and systemic illness. Severe PRDC cases result in pigs unable to rise, in respiratory distress, and losing weight rapidly. The chronic subclinical form — prevalent in many finishing units — causes ongoing respiratory discomfort and reduced growth that represents a prolonged welfare harm often invisible to casual observation. Ammonia accumulation in poorly ventilated housing is an immediate welfare concern — it irritates eyes and airways and causes pain at levels commonly found in inadequately managed pig buildings. The welfare case for investment in appropriate ventilation, stocking density management, and biosecurity is compelling, with co-benefits for productivity.