How do dogs communicate with cats?
Dogs and cats that live together do develop their own ways to communicate with one another--I live with 2 dogs and 3 cats; and part of the joy of sharing my home with them is watching how they do interact. Sometimes they snuggle up with one another, and groom each other. Other times, the dog will want to be friendly, the cat needs some space--they communicate the same way with one another as they do humans--wags and barks, nips & purrs, scratches and kisses.
My parents had an Old English Sheepdog named Moosebay Elvis who was the great protector God Dog of many kittens and cats--Elvis would show my father where the feral cats had litters on the farm by very gently lifting the newborn kittens in his mouth and holding them up for my father's inspection. Then Elvis would set the kitten back in the nest--never leaving a mark on the kitten. If the cats sensed a predator, they would leap into Elvis's pen and run behind him or into his house for protection.