Something inside the cage of Brubaker on Season 1 chapter 1

I noticed that on chapter one from season 1, there is a scene where Clark DeBussy went out from interrogating room to a tent where Brubaker is, while Brubaker is talking, the camera is shifting into a cage with red light under Brubaker. It appears there is some sort of a pet, a dog. do anyone know what is this? And any reference on this?