Advancing and refining euthanasia methods in laboratory rodents

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The overwhelming majority of laboratory rodents (rats and mice) are killed when research projects end. This process is intended to be humane, providing a rapid, pain-free death ("euthanasia"). Unfortunately, as we understand more about animal behaviour and physiology, it is unclear if current methods truly achieve euthanasia. Two of the most common methods are overdose with carbon dioxide gas and overdose with an inhaled or injected anesthetic drug. There are concerns about each of these methods: 1. The point at which animals become unconscious with carbon dioxide gas is not well-established. It is possible that pain (carbon dioxide irritates the airways) is experienced before this occurs. 2. Rodents find inhaled anesthetic gas aversive. The cause of this is unknown. 3. Overdose with injected anesthetic usually causes unconsciousness and death quickly. However, in up to 20% of rodents, the injected drug ends up in the wrong place and there is a delay before unconsciousness occurs. It is possible that pain occurs during this delay as the anesthetic solution is strongly alkali. My program of research focuses upon understanding how these different methods affect laboratory rodents. The goal of this research is to identify if pain may be occurring before animals become unconscious and to find better methods, with the aim of achieving euthanasia. Tools we use include assessing the presence of pain by evaluating facial expression and monitoring brain wave activity (electroencephalograms) for signs of pain and death. I anticipate identifying both a novel euthanasia method and also offering refinements to existing methods through a better understanding of their strengths and limitations. The assessment methods used and developed will be applicable to evaluating future euthanasia methods. The results of this research have important and far reaching consequences for how we manage end of life care for laboratory rodents within Canada but also internationally, with the potential to improve care for millions of animals annually (in excess of 15 million rodents are used in biomedical research annually between the EU, Canada and the UK). Additionally, this research will provide research training for students from the natural sciences, engineering and veterinary medicine, preparing them for careers in universities, clinical practice and industry.