Abstract: An animal shipping cage is provided that can be a single size or in two or more different sizes. The cages are stackable, one on top of the other which has a number of benefits when shipping small animals. A cage of a single size is configured to have one cage stacked on top of another. Cages of two different sizes are configured to be stacked on top of each other in the same stack. Having a combination of cages, a small cage and a large cage, which can be stacked on top of each other in a secure fashion provides significant benefits when shipping a large number of different types of small animals. In one embodiment, a secure lock is provided that ensures the lid to the cage can only be opened by an intentional action of high force and confirmation obtained that it was not opened during shipment.