That kitty trusts that dog with its life.
I had a cat and a dog, where they trusted each other so much, the cat used to sleep next to the dog in the winter, and she had her kittens in the dog's sleeping area, and the dog wouldn't go in there to lie down, so as not to hurt the kittens. That's how we found out where they were.
As pets, my dogs and cats have gotten along wonderfully. Those two are just playing, but if they weren't, the cat would have the advantage and the dog would know it.