Quote Originally Posted by jitami View Post
What would your recommendation be for both(mice & snakes) Stefan? I've thought about raising feeder mice and always planned on using CO2... so it doesn't work so well on newborns? Does it just take longer, or is there some stress to the mice involved?
Snakes: stunning blow to the back of the head, decapitation and destruction of the brain. Or have a vet inject the substances you can't own. Why? Because freezing causes discomfort and decapitation alone doesn't kill the snake right away.

Newborn mice (a few days old, max): freezer. Why? They supposedly die before ice crystals begin to form. According to what I've heard, they completely shut down in less than a minute. CO2 doesn't kill them right away, they'll hold their breath and can do so for quite some time. Alternatively snap the neck.

Less than 10 days of age, but not quite newborn anymore: Snap the neck. Won't shut down as easily in the freezer and they still have that damn reflex.

Mice older than that should be killed with CO2.

Note that I haven't actually tested most of these methods for legal reasons, so this is just a collection of recommendations I've picked up over the years. People use other methods as well, including throwing mice against the wall or floor or swinging them by the tail against some hard surface. No doubt those methods will get the job done, but at this point, I wouldn't recommend or use them. One method that is pretty quick, judging by what I've seen, is putting the mouse on a hard surface, grabbing the mouse by the tail, putting a screwdriver, pencil or tweezers across the neck, push it down against the surface while you simultaneously pull it upwards at an angle.

Local animal protection legislation only permits lethal injection, gassing with an appropriate gas (one that causes instant loss of consciousness), electrocution (depending on whether the animal is considered a production animal or a pet), shooting in the brains, and if the animal is less than 3 days of age, striking it on the head. I recommend following your local laws.