Pie's been out in his paddock now for two nights. He clearly wishes he had another horse out there with him. On the first night he did some running and calling, although not a lot, and on the second night he spent some time pacing up and down the fence line. But he's settling down, and I expect each day will be better, although he's very grateful to be back with the others at turnout time. The weather's been pretty cold, with wind chills below zero at night, and there's some evidence that he's been using his shed, and he's drinking well from his heated water trough.
The paddock had some grass and weedy (non-toxic) stuff under the snow, and the first night he spent quite a bit of time digging in the snow and eating the bits he found. That, plus the anxiety of the first night, gave him some loose manure, but that had cleared up by the middle of the next day. This morning, his manure was normal and he'd eaten his hay almost completely, which means he wasn't eating as much of the grass/weeds - I wouldn't put it past him to be smart enough to associate what he'd been eating with not feeling so well and to have decided to eat the hay instead.
This morning his hock sore was dry and scabbed over - I'm keeping my fingers crossed on that.
So far so good!