Absolutely! A friend of mine was living with me for a while and he had 2 ratties. One of them died at home and the other one, we had to take to an emergency clinic on a Sunday to have euthanized
He also had tumors (in fact, was scheduled to have one removed later that week) and decompensated quickly. Although it was hard (for me too, I really got attached to the little buggers: I was there when he adopted them), I think it was the right decision.
to you!