Long ago, Humans genetically modified a certain group of people to live out their fantasies. These people were modified to become Furries, a group of human-like animals. They may have forgotten to mention that Furries were going to be a slave race. However, this genetic modification had side-effects. Furries grew. A lot. It was common practice to execute furries before they grew so large, they couldn't work in mines anymore. They could also stretch and control their bodies, to the level where they could probably stuff a human inside of them. Heck, someone could probably survive in there, if the Furry wanted it. However, they're just a slave race. I mean, what could go wrong in this situation? It's not like this is a vore fiction or anything.