Assessment of welfare of pigs during CO2 anaesthesia

We assessed the well being of pigs during handling and CO2 anaesthesia. Results for heart rate showed that stress appeared greater during handling just before anaesthesia and in the first 40 seconds spent in the cradle. Thereafter, lowered heart rate suggested the pigs were unconscious. As regards behaviour, theanaesthesia took place in several steps during which the animals’ reactions were fairly characteristic. Recoil, inhalation and excitation phases suggested a stressful, or even painful situation for the pigs. Postural collapse and convulsions indicated loss of consciousness. Thus during CO2 anaesthesia both the period of gas inhalation and that of excitation of the pigs are problematic for ensuring animal welfare.