If this situation occurs in the future, please learn how to do cervical dislocation (neck breaking) or just bash the poor animal hard against a wall. Better yet, find a supplier of dry ice so you can gas them. It will take a mammal AGES to freeze to death and be incredibly painful in the meanwhile. That isn't meant to make you feel bad, just trying to pass along some information.

The guy at the Petstore was just - there are no words. I'm sorry.