I wasn't sure whether Sofy would be upset or worried to be left, but as I was getting Wiggle's collar and lead on, I had given Sofy a couple of chewy sticks and we'd slipped out of the house while she was chewing.
We'd ended up being nearly an hour so when I pulled up outside the house, was half expecting to hear barking or some sign that Sofy wasn't impressed by being left. But in fact, I got out of the car, up to the front door and looked through to see Sofy sitting in the living room!
She greeted Wiggle like he had been gone forever, excitedly wiggling and wagging, taking in the smells of the vet and where he'd been. There's not usually a reason to leave either of them on their own, but its good to know that Sofy wasn't at all upset or distressed. And didn't sulk at us too much!