Respiratory disease is a leading cause of welfare harm and production loss in commercial pig farming, driven by a complex of interacting pathogens and environmental factors.
Respiratory disease causes significant welfare harm through breathlessness, pain, fever, and reduced ability to engage in normal behaviors. Pigs in PRDC-affected units show reduced feed intake, lethargy, coughing, and failure to thrive. Severely affected pigs in conventional housing have limited options for self-removal from infected airspace or access to cleaner environments. The chronic welfare burden of subclinical respiratory disease - reduced growth, immune suppression, and discomfort - is invisible to casual observation but represents ongoing suffering in many commercial units. Reducing stocking density, improving ventilation, and implementing all-in-all-out management by age group are among the most effective welfare interventions.