I've owned fifteen or so gerbils in my time and I have never seen one get better once it hit the hunched-over-and-bedraggled stage. Maybe it was the fluids and antibiotics; maybe it was the Anglepoise lamp aimed at his bedding for warmth, as recommended by Gerbils Anonymous. And maybe it was you lot and your good wishes and thoughts.
Obviously I loved the gerbs as soon as I got them, but now one of them has been at death's door and come back, I'm just crazy about them. I don't think I realised what a large emotional investment I'd made until I thought I was going to lose Pin.
Here he is last night, enjoying a pine cone (the gerbil equivalent of crack):