The sweatshirt sounds like a good idea. I go to the thrift store and get baby blankets and tiny baby shirts for Ricky & Lucy Tu. Lucy Tu had a fantastic jacket (see below) but outgrew it. Both of them like to sleep under the covers so that helps. When they get really cold and are shivering like crazy, I put their baby blankets in the dryer for a quick warm up and then cover them up with them. They love that. Lucy Tu likes to go in the pocket of my robe while I am wearing it (see below) Our daughter bought both of them a Harley Davidson leather jacket but I prefer to put something soft on them. Even though we live in Florida, Chi's are almost always cold.