CO2 stunning is the most widely used method for stunning pigs before slaughter but causes significant distress - research into less aversive alternatives is advancing.
CO2 pig stunning welfare represents a case where a widely used standard method has well-documented welfare problems that have not yet driven widespread adoption of alternatives. The science is clear that high-CO2 stunning causes significant distress during the induction period. The welfare improvement case for argon-based alternatives is strong but economic barriers have slowed transition. Consumer and retailer pressure for welfare improvements at slaughter - including specifying stunning method as part of welfare standards - creates market incentives for investment in better systems. Regulatory approaches requiring minimum welfare standards for stunning have driven some improvements but the pace has been slower than the welfare evidence supports.