Swine influenza viruses circulate in pig populations worldwide, causing welfare harms and representing an ongoing zoonotic disease risk requiring integrated welfare and biosecurity management.
Swine influenza is both a welfare problem for individual pigs and an example of the One Health connections between farm animal welfare and public health. Sick pigs experience genuine illness — fever, respiratory distress, muscle pain — for the duration of each infection episode. In large intensive operations, respiratory disease spreads rapidly through pig populations, causing welfare losses across thousands of animals simultaneously. The zoonotic dimension means that conditions enabling rapid viral evolution in dense pig populations — exactly the conditions of intensive farming — also create pandemic risks. Improving pig welfare through reduced density and better housing would simultaneously improve pig health and reduce pandemic risk.