I'm sure someone has. But Muttley got a new bed for Xmas... and since her doggy arthritis in her back legs is getting worse, I sacrificed a brand new electric blanket that was never used to cover it. That went over well. It's all junk anyway. I have no idea, but she seems to like it. It has an 8 hour "off" timer" on it. She's no spring chicken, but 4/20 (her birthday for real) is only 4 months away. 17 years old... but someone corrected me and said it is only 16.... but the photo of her as a pup lacked a date, so I'm pretty sure it's 17. I guess we'll have to make the heated dog beds in Vietnam... a Trumpy favorite. He just doesn't realize it yet.
Wary of EM burning (slightly) and fire risk outside I put in a big coil of clear tubing under our old farm dogs bed and have a water pump with heated reservoir similar to an under sink tank. In retrospect, I maybe should have used aluminium tube for efficency but it still works. Any old car radiator would be fine too. When the pump comes on, Alexa controlled, he hears it and straight to the bed.