Enzootic pneumonia caused by Mycoplasma hyopneumoniae is endemic in most UK pig herds, causing chronic welfare compromise and significant production losses.
Enzootic pneumonia causes chronic welfare compromise in affected pigs: persistent coughing is both physically demanding and distressing, and the chronic inflammation reduces immune function and predisposes to more severe secondary bacterial infections. Pigs with pneumonia show reduced appetite and activity that impair welfare beyond the respiratory disease itself. The chronic nature of Mycoplasma infection, persisting for weeks to months in individual animals, means welfare compromise is prolonged rather than acute. Herd-level vaccination programmes reduce the prevalence and severity of clinical disease, directly improving individual pig welfare at population scale. Housing and ventilation improvements that reduce disease transmission represent the most durable welfare improvements.