My old cat, Orville, had my last dog Gus so terrified of him it was insane, but when King and Molly came along, he found out that King wasn't scared of him, but he actually enjoyed the cat's tantrums he had when King tried to play, or just sleep with him. When we first got the pups, they were almost exactly half the size and weight of the cat, who was very large at 24 pounds, and a real handful when he was angry. We kept them totally apart for a few days then put the pups in their crate and let Orville see them. He seemed fine with it, and just laid there in front of the crate, toughing their noses with his foot. We the pups out, and the fun began.
Molly almost totally ignored him, but King made it his "job" to watch the cat at all times, and he was very dedicated to that job. He would crawl under the bed and pull Orville out. Orville would be very angry about it, and would hiss and spit and howl about being pulled out, and King though it was great and would play bow to Orville who would scream like he was being killed anytime King approached. King loved it! Slowly, Orville realized that King wasn't out to hurt him, and as King approached 30 pounds, he began to try to play with him. Sometimes. One day I caught them sleeping together on my bed. I don't think Orville knew King was there, as soon as he woke up, he looked at King and screamed and took off.
Just about the time that Orville actually could be near King without being nervous about it, he went sour and had to be put down. He probably had cancer. He was about 17, so it wasn't a surprise. King was very upset and looked for the cat for a couple of weeks.