Pig Respiratory Disease: Enzootic Pneumonia and Welfare

Enzootic pneumonia and other respiratory diseases are major causes of suffering in pigs globally. Understanding their causes and welfare impact is essential for improving pig health.

Key Facts

Enzootic pneumonia, caused primarily by Mycoplasma hyopneumoniae, is one of the most widespread diseases in commercial pig production.
The disease causes chronic coughing, reduced growth rates, and lung consolidation (scarring) that impairs lifelong respiratory function.
PRDC (Porcine Respiratory Disease Complex) involves multiple pathogens including Mycoplasma, PRRSv, influenza, and Haemophilus parasuis.
Overcrowding, poor ventilation, mixing of pigs from different sources, and weaning stress all increase respiratory disease risk.
Lung lesions found at slaughter reveal that 30-50% of pigs in many production systems have experienced significant pneumonia.
Antibiotic treatment reduces acute suffering but does not reverse lung damage already incurred.
Vaccination programs combined with all-in/all-out pig flow and improved ventilation significantly reduce disease burden.

Welfare Considerations

Pigs with respiratory disease experience chronic discomfort — persistent coughing, labored breathing, and reduced ability to exercise or engage in natural behaviors. Subclinical disease (no obvious coughing but significant lung damage) is pervasive and indicates that many pigs suffer without visible symptoms that would prompt treatment. The connection between intensive production conditions — overcrowding, poor air quality, stress — and respiratory disease makes this a systemic welfare issue rather than an individual health problem. Improving pig welfare requires addressing the environmental and management conditions that predispose pigs to disease, not merely treating illness after it occurs. Reducing ammonia levels, improving ventilation, and maintaining lower stocking densities are all evidence-based welfare interventions.

What You Can Do

Support pig welfare certification schemes that require adequate ventilation and stocking density standards.
Choose pork from producers who demonstrate low respiratory disease mortality rates and good herd health records.
Reduce pork consumption or shift to plant-based alternatives to lower demand from high-disease-burden systems.
Advocate for mandatory ventilation and stocking density standards in pig housing regulations.
Support research into alternatives to antibiotics for respiratory disease management, including improved vaccines.
Ask food companies and retailers about their pig health and welfare sourcing standards.