[GarterGuy]

I think a lot use the CO2 method....also some places get there mice from labs that use them for other purposes....especially to work with there blood (if you've ever bought mice called "cut throats"..that's where they came from). The labs use isofluorene to "gas" them ( I actually did some work with a large testing lab making iosfluorene detectors so they could tell if the "kill boxes" were leaking). Freezing ectotherms, like reptiles is humane, but mice are mammals just like us.....freezing to death is not a great way to go. By the time they'd "slow down" they've already suffered from the freezing of their extremities (tails, feet, ears)...which if you've ever been outside for a long time in the winter....it's VERY painful! You'd probably be best off actually contacting some of the rodent breeders and asking them what they use.

---Roy