My cat does the same but he has my legs on either side of him. He loves the position as he receives the maximum amount of warmth from me. It usually happens when I am in bed on the computer. He conveniently moves off my lap so I can use the computer and moves down my legs into the sandwich position.
The behavior is based on the domestic cat’s love of a warm ambient temperature, a trait inherited from the domestic cat’s wild cat ancestor. There is also the emotional warmth that such a sleeping position provides both for the cat and the dogs. It is another example of interspecies relationships benefiting both species.
SOME INTERSPECIES ARTICLES SELECTED AT RANDOM:
