Evaluation of Different Gases and Gas Combinations for On-Farm Euthanasia of Pre-Weaned Pigs

There are times on a swine farm when pigs become ill or injured and must be euthanised. Blunt force trauma to the head is currently the most commonly employed method for on-farm euthanasia of pre-weaned piglets. When performed correctly, loss of consciousness is rapid, but the potential for delivery of sub-lethal blows, along with aesthetic unacceptability to many operators, has led to the need for alternative methods to be developed. The practice of using carbon dioxide (CO2) to euthanise piglets during the pre-weaning period is becoming more common on-farm in the United States; however, animals may display behavioural and/or physiological signs of stress or aversion in response to CO2 inhalation. Inducing anoxia using argon (Ar) gas may cause less aversion or stress and thus be preferable to using CO2. Therefore, the aim of this research was to evaluate the effects of 100% CO2, 100% Ar or CO2 and Ar combined (60% Ar/40% CO2) on piglet welfare during euthanasia. The results from this research suggest that using CO2, Ar or a 60% Ar/40% CO2 mixture causes stress to piglets prior to loss of consciousness and hence alternative methods of euthanasia need to be evaluated