Pig Respiratory Disease: Welfare in Intensive Housing Systems

Respiratory disease is the most economically significant and welfare-impactful disease complex in commercial pig farming, driven by intensive housing conditions and pathogen pressure.

Key Facts

Porcine Respiratory Disease Complex (PRDC) involves interactions between multiple pathogens including PRRSV, Mycoplasma, and Influenza A.
Respiratory disease causes coughing, fever, reduced growth, and death in affected pigs.
Intensive housing at high stocking densities, poor ventilation, and temperature fluctuations predispose pigs to PRDC.
Ammonia from urine decomposition in poorly ventilated housing damages respiratory epithelium and increases susceptibility.
Porcine reproductive and respiratory syndrome virus (PRRSV) is responsible for billions of dollars in losses annually.
Antibiotic use for respiratory disease is a major contributor to antimicrobial resistance concerns.
Vaccination programmes targeting key PRDC pathogens reduce severity but rarely eliminate the complex.
Better ventilation design and reduced stocking density consistently improve respiratory health outcomes.

Welfare Considerations

Respiratory disease in pigs causes acute suffering — fever, laboured breathing, coughing, and the systemic malaise of pneumonia. In intensive settings where hundreds of pigs share airspace, disease spreads rapidly and affects large proportions of the group. The root cause — high ammonia, poor ventilation, high stocking density — reflects a system design that prioritises economics over health. Pigs that develop secondary complications including pleuritis suffer chronic chest pain with every breath. Post-mortem surveys regularly reveal pleurisy and adhesions in a substantial proportion of slaughtered pigs, indicating that subclinical respiratory disease causing chronic discomfort is far more prevalent than clinical outbreaks suggest. Addressing ventilation, stocking density, and all-in-all-out management is both a welfare and economic imperative.

What You Can Do

Support pork certification schemes that include ventilation standards and maximum stocking density requirements.
Ask producers and retailers about ammonia monitoring and air quality management in their supply chains.
Advocate for respiratory disease prevalence reporting at slaughter as a welfare outcome indicator.
Support research into PRRSV vaccine development and non-antibiotic disease management strategies.
Choose pork from outdoor or free-range systems where natural ventilation and lower density reduce respiratory risk.
Engage with antibiotic stewardship programmes that target respiratory disease as a priority area.