Pig Pneumonia: Welfare and Prevention on Farm

Understanding the welfare impact of respiratory disease in pigs, the pathogens involved and effective herd-level prevention strategies.

Key Facts

Enzootic pneumonia caused by Mycoplasma hyopneumoniae affects up to 80% of commercial pig herds globally
Respiratory disease is the leading cause of economic loss in pig production and a major welfare concern
Coinfection with PRRSV and swine influenza dramatically worsens disease severity
Stocking density, poor ventilation and mixing of different-age groups are primary risk factors
Vaccination can reduce severity but does not eliminate infection in high-pressure environments
Subclinical pneumonia suppresses growth and causes persistent discomfort without obvious outward signs

Welfare Considerations

Respiratory disease in pigs causes dyspnoea, pyrexia, anorexia and chronic discomfort that is often underestimated because pigs mask illness as a prey-species behaviour. Subclinical infection is particularly insidious — lungs show consolidation at slaughter even in pigs that appeared clinically normal, indicating widespread undetected suffering. The Five Domains framework highlights that impaired respiratory function affects not only physical health but also mental state through reduced capacity for normal exploratory behaviour. Herd-level prevention through environmental management is far more effective and humane than treating outbreaks after they occur.

What You Can Do

Audit ventilation quarterly — maintain recommended air flow rates and eliminate draughts at pig level
Adopt all-in-all-out management to break transmission cycles between age groups
Implement a respiratory health monitoring programme with regular slaughterhouse lung-scoring feedback
Vaccinate breeding sows for M. hyopneumoniae to reduce vertical transmission to piglets
Work with your vet to develop a written health plan with antibiotic stewardship protocols
Reduce stocking density if disease pressure is high — space investment pays in welfare and productivity