Porcine Stress Syndrome (PSS) is a genetic disorder linked to selective breeding for lean muscle mass. Its history illustrates how breeding decisions can create widespread, preventable welfare problems.
The history of PSS in pigs illustrates a principle with broad applicability: selective breeding for production traits can inadvertently select for welfare problems if welfare traits are not explicitly monitored. The solution — genetic testing and selection against problematic alleles — worked effectively once identified. This precedent supports proactive welfare genetics: screening breeding lines for welfare-relevant traits before problems become endemic. Investment in welfare genomics is one of the highest-leverage interventions available for preventing future welfare crises in farmed animal populations.