Respiratory disease is the most costly and welfare-significant health problem in commercial pig production, causing chronic suffering in millions of animals annually. Prevention through improved housing and vaccination is far preferable to treatment.
Respiratory disease in pigs causes chronic suffering that is frequently underappreciated because affected animals continue to grow and eat, masking the degree of impairment. Pigs with enzootic pneumonia experience persistent coughing, laboured breathing, and reduced exercise tolerance — signs of genuine respiratory distress. Severe PRRS outbreaks cause acute systemic illness with fever, lethargy, and high mortality in young pigs. The root causes of high respiratory disease prevalence are largely environmental: high stocking density, poor ventilation, inadequate all-in-all-out management, and excessive ammonia levels create conditions where respiratory pathogens thrive. Addressing these conditions improves both welfare and productivity, providing a clear economic incentive for welfare-motivated management changes.