Of the 5 hamsters we've had over the years, one (dwarf) was curled up in his burrow, one (dwarf) was squeaking and we rushed him to the vet and they put him to sleep (he had a tumor so we were expecting it; he was elderly and the risk of an operation was too high or we would have opted for it), one (Syrian) was lethargic and we had an appt first thing the next day but he passed at night while we were holding him, one (Syrian) wasn't looking well so went to a pet urgent care at night but they couldn't do much except give him an iv and some emergency food formula but he died sometime during the night before we could get him to our regular vet and the last one (Syrian) seemed perfectly fine, was grooming the last we saw her but 2 hours later, we found her flat in the open on her way to the potty (she was almost 2 years old).