Respiratory disease is endemic in commercial pig production and closely linked to air quality in indoor housing systems. Managing ammonia, dust, and pathogens in pig houses is both a welfare and a production challenge.
Respiratory welfare in pigs involves both acute infection suffering and chronic low-level respiratory irritation from poor air quality. Pigs with lung lesions at slaughter show reduced growth performance and increased medication use during their lives - these production indicators correlate with welfare compromise. The lung scoring system at slaughter is one of the few direct welfare outcome measures routinely collected in commercial pig systems, making it a valuable benchmark. Welfare improvements in respiratory health require addressing ventilation, stocking density, management of sick animals, and antibiotic use protocols in combination.