My rat, Big Mama, suddenly died. She was fine earlier but I just found her dead (and partially eaten by her family). Other than the chewing done on her, her body is fine. She wasn't killed by the others. She's gone rigor in a peaceful position and there was no blood in the cage. (Rats do mourn with cannibalism). Just wondering if anyone knows what could have happened. She was older, 3, but I have a rat who's nearly 5. Old age?