Have you tried a self warming bed or blanket?? They don't have any cords or electricity or no microwaving and no risk of getting too hot. The reflect body heat keeping you nice and warm. I love them, they work great!!
And they are cheap to buy or cheap to make. Here is a link so you can see something like what I am talking about.
http://www.petedge.com/shopping/prod...ProductID=4518
Also here is a link to make one yourself. I am a member of spoiled maltese and they posted on how to make one.
http://spoiledmaltese.com/forum/inde...opic=17329&hl=