Everyone agrees drowning is really not humane but nitrogen isn't approved either (rodents are not humans and so they might react to things like inert gas hypoxi

Everyone agrees drowning is really not humane but nitrogen isn't approved either (rodents are not humans and so they might react to things like inert gas hypoxia differently). CO2 is common in labs though lab rats/mice do show aversion to CO2 which is interpreted to mean that it causes distress. So there's been ongoing debate for 20+ years over how humane CO2 is and what the correct flow rate should be and if oxygen should be added (or not) or other gasses (or not).[1] Something physical like direct concussion/blunt force trauma followed up by another method might be better[2] (needs more studying) but there's also issues with physical methods because they require more skill to do correctly (or tools/machines developed to negate the skill factor). Also operators dislike physical methods compared to gassing[1] so what's most practical might end up the standard[3] even if it may not be the most humane. I mean, theoretically if you could instantly crush a mouse, faster than brain/nerve signals can travel, that would be humane, right? But then a human has to deal with a gruesome crushed mouse. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5035945/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5035945/ [2] https://journals.sagepub.com/doi/full/10.1177/00236772221097472 https://journals.sagepub.com/doi/full/10.1177/00236772221097... [3] https://www.avma.org/sites/default/files/2020-02/Guidelines-on-Euthanasia-2020.pdf https://www.avma.org/sites/default/files/2020-02/Guidelines-...