[andbberger]

> A second ethical issue with studies with mice is that often the unfortunate phd student tasked with dispatching the mice will not have been taught any way to do so and will have to try to come up with something on the spot. This can be quite traumatic for both parties.

uhhhhhh are you sure about that?? This strikes me as a flagrant violation of policy. Animal studies are heavily regulated.

In my experience, (and mind you I've only ever worked adjacent to animal labs, not directly in them) there is always a canister of CO2 and a euthanization chamber on standby in experiments where there is a risk of injuring the mice.

[samatman]

While this is standard, it shouldn't be.

Mammals sense CO2 buildup, not oxygen depletion. By smothering with CO2, the mice spend their last moments desperate to breathe and unable to.

If they were to use nitrogen instead, the mice, having no way to know they've been deprived of oxygen, would just pass out and die.

[andbberger]

There's a good chance I have that wrong and they use nitrogen. Like I said, I don't work in animal labs, just adjacent to them.

[nothrabannosir]

I knew someone who worked with lab rats; her job was to kill them and she had to use CO2.

[HorstG]

afaik (second hand) CO2 is used for safety reasons, humans can sense a CO2 poisoning but not an excess of nitrogen.

[throwmamatrain]

As for methods here's the list: https://animal.research.uiowa.edu/iacuc-guidelines-euthanasi...

In my work, our approved methods were isoflurane and decapitation. In some types of experiments CO2 will interfere with your result.

[dan-robertson]

Probably should substitute “often” for “occasionally”. I’ve edited the comment.

I suppose there are other factors too, eg the student not thinking to say they don’t know how to kill a mouse and their advisor not thinking to ask.