"Its a 3 dog night..."

I was once told that hunters guage the "coldness" of the night by how many dogs it takes to keep them warm,
and discovered that they do in fact release a lot of heat!

On cold nights we let our 3 dogs and our cat on the bed, and hey presto, toasty warm without an electric blanket, or use of a hot water bottle!

You can kick them off (ie move them gently) when you have warmed up

And they like it too...