I would guess that they modify some rats to give them much less hair, then subject the bare skin to ultraviolet radiation (or whatever else causes skin cancer) and observe the effects. I consider this unnecessarily cruel - why can't they just experiment on bacteria or ants?
i dont quite understand the wording of this question. if you mean did research and experimentation cause cancer to be a problem with rats then yes. because most rats are descended from the lab rats, pet rats are prone to cancer.