What is the most humane way to "brain" a rat?

[Stewart_Reptiles]

I'm a biologist, and many people I know have worked in labs that euthanized mice/rats using CO2 chambers. Everyone I've ever talked to says the same thing you did about CO2 chambers not being very humane.

Have you done it yourself?

I can tell you that everyone you talked to does not do it right and too much CO2 is filling the kill tank at once hence the gasping and panic.

When done right they will slowly fall asleep, this can be achieve with a CO2 regulator, than again people need to educate themselves.