A lot of stores carry heated pet pads.Try searching on Amazon, Petco, Petsmart.
I don't have that problem.I have an electric blanket on my side of the bed.My wife and dog, a pretty good sized black lab cross, goes to bed earlier than I do.Most nights it's a fight to get my share of the bed when I do go to bed.

If God wanted you to walk and carry things on your back, He would not have invented stirrups and pack saddles