Quote Originally Posted by Shenzi Sixaxis View Post
YouTube - Mouse CO2
YouTube - mini Co2 mice, rat euthanize Kit

Honestly, IMO, Co2 gassing can't be humane. They're aware of what happens and suffocate. Maybe it's not as bad as having your throat smashed in, but suffocation is suffocation. For me, I would go the way of cervical dislocation or a smack to the head unless I was dealing with large rats or LOTS of rodents.
If you do it with the cooler, they don't get hit with such a large amount and suffocate. The way that the first video shows is too much CO2 too fast. Then they choke to death and it's a horrible way to go.

If you do the cooler with dry ice it introduces the CO2 much slower and allows them to go to sleep before totally removing the oxygen. Notice that video took only about 1 min before they died? That's too fast. It should take 4-5 mins so that they go off into la la land before they stop breathing. The twitching and the flip over was a dead give away (no pun intended) that they were receiving too much CO2 too fast. As I said, put them in a cooler and it's much simpler and much cheaper than getting a CO2 tank and doing all that jazz.