Has this been happening for a while, or is it a sudden thing? Both my boys act the same way when home but the moment they step outside, they're ready to run. I don't know about doxies..but it varies from dog to dog. Shelties are *supposed* to be quite energetic but my two would gladly take a 12 hour nap with me any day.

If it's a sudden thing, a vet check is in order. If it's the way she's been for some time, I wouldn't be concerned.

You could try maybe playing ball or something in the house. I'm not in a very cold part of Canada but the rain is harsh. I try to get them to fetch when it's raining and adding in some obedience work to poop them out. From looking at the way Kai and Kaedyn act, they don't look like they need the work (at home) but it never hurts to get a lethargic acting dog to exercise.