Not all pet stores have a "back." Very hard to check a pulse or heartbeat on a pinky mouse. And I will pass on being the employee exposed to carbon monoxide on a regular basis.

Being paralyzed while drugs seize your heart function doesn't sound like a lot of fun to me. I'd pick a freezer over a lethal injection. This is an awful conversation. Lets go back to talking about the small child being mauled to death. Less depressing.