That's adorable.
When I was a kid, my twin brother's kitten was "best friends" with my German Shepherd/Husky mix. (She was huge like a wolf). After she had puppies, his cat nursed on her long after the pups were gone. Bear (the dog) used to carry the cat all over the yard either in mouth by scruff of the neck, or riding on her back. When she carried her in the mouth, the cat looked really floppy and we all thought oh no, she killed her.
![LOL LOL](./images/smilies/emot-LOL.gif)
They used to "play fight" it was so weird and hilarious. Then they would lie down, the cat would suckle and they would go to sleep. They were both females, it was so "odd" to us. LOL