Pig slaughter welfare depends critically on pre-slaughter handling and stunning method, with high-concentration CO2 stunning increasingly controversial due to evidence of aversion and distress.
Pig CO2 stunning represents a significant welfare compromise that is being perpetuated by the economic convenience of a method that requires no individual animal handling. The evidence against CO2 is substantial: pigs show behavioral responses consistent with pain and panic during the exposure period before losing consciousness, and these responses satisfy criteria for genuine aversive experience. The alternative - inert gas mixtures like argon or nitrogen - avoids the caustic mucosal irritation that makes CO2 aversive while achieving rapid insensibility. The transition from CO2 to inert gas stunning requires capital investment in gas infrastructure but would improve the welfare of millions of pigs annually. Consumer and retailer pressure has begun to move some major producers toward inert gas systems.