I did have one rat with no external signs whatsoever of tumors or illness, that suddenly died one day while I was at work. The only sign on her body I could find to explain what happened was a little of blood coming out of her rear end... any idea what that could have been?
That's a hard thing about ratties. They won't show symptoms of disease until they cannot mask it any longer. I've got one girl who had a stroke (or a slow-growing brain tumor) and she walks around with her head tilted at nearly 90 degrees, but her appetite and playfulness are still in top form.
Had one boy we rescued who was the seeming model of health except for he would, two or three times a day, shriek in pain for no apparent reason. After two days of that, we took him to the vet and learned that one of his hind legs was *broken*. After he got the treatment he needed (and three weeks in isolation...which had to suck), he was fine. But that was a real object lesson for me.
I did have one rat with no external signs whatsoever of tumors or illness, that suddenly died one day while I was at work. The only sign on her body I could find to explain what happened was a little of blood coming out of her rear end... any idea what that could have been?
Far too many things could have caused it. Could have been megacolon (that typically kills rats in young adulthood...and there's no treatment for it). Could have been a respiratory illness that brought on sudden distress (that tends to make blood vessels burst in various locations), could have been a stroke. No way to tell for sure without an autopsy.
Sorry for your loss, though. Never easy to lose a furbaby.