So my rats are still hanging on, their endurance is remarkable. One got about as close as you can get to dying without actually doing so; crying blood (for crying out loud!) pretty much everyone was convinced hours to live was the deal here and if the vet hadn't been closed we would have gone there. (They recommended juice through an eyedropper and raw mince as a holdover though.)
Next day, if not right as rain at least a little overcast. That was a week an a half ago and she's still not slowing down. Oddly enough said rat has always been rather ambivalent about leaving their nice warm cage in the past, taking the view that one needs little more than food, water and bed in convenient walking distance. However since nearly dying she seems far more interested in Out, I'd like to think this is because she wants to see the world before she dies, but I suspect it's just to get more of that sweet, sweet eyedropper juice.