ROFLMAO your cairn sounds just like my parson russell.
She tends to suffer from the cold when out in the wet or if she's not moving about for a while when out.
When I was out camping last year I went out in the dark for a pee in the pouring rain and she followed me. Stood for ages in the dark waiting for her to come back and in the end I went back into the tent as I was soaking. Pushed my feet into the sleeping bag and there she was at the bottom, all warm and cosy. Certainly not stupid!