Rat Terrier Poodle Mix What Is The Best Way To Introduce A New Cat, Or Kitten Into A Dog Household Where The Dog Is 4 Years Old.?

What is the best way to introduce a new cat, or kitten into a dog household where the dog is 4 years old.? - rat terrier poodle mix

I had my dog since he was still a puppy and that was it, the animals, others do not () outside of my roommate. She is only 19 pounds and is a rat terrier / poodle mix (I heard). I wonder what is the best way to introduce my dog a new cat. I do not know whether a cat would be easier, or a cat. What are your thoughts? Thanks