One of my military spouse friends recently went on a long vacation with her family. Before leaving she asked if anyone would be able to watch her dog, Jet, while they were gone. I volunteered. Charles has been wanting to get a dog and I was curious how the cats would handle one being in the house for an extended period of time. Prior to this dog sitting experience they had only been exposed to Stella, a pug/chihuahua mix. And that was just for a few days. They spent those days hiding under the couch.
Jet arrived and the cats promptly hid, as expected. Calvin spent the first several days upstairs hiding under the covers. I don't think they ate or went to the bathroom at all in the beginning of Jet's visit.
Eventually Hobbes, our more friendly and curious little one, came down. At first it would just be for a little bit until Jet became too interested in him. And then finally Hobbes let Jet smell him and he was more comfortable coming downstairs for longer periods of time.
Finally on the last day Calvin came downstairs. But it was only for a couple of minutes. It gave me hope, though!