[AnmlLvr14]

I think it may have been mentioned somewhere above: they gas them with CO2. That way no chemicals are injected into them.

I have worked at two different zoos and all animals are fed pre-killed prey (except for feeder insects). We would feed live pinkies to some animals, but never anything older than a pinkie. Before feeding snakes, the mice/rats were put into warm water. After all, snakes look for warmth rather than something moving.