We bought a baby gate before bringing our new puppy home and we put it up in the doorway to our rec room. Before bringing him in we made sure the cat was on the other side of the gate, a safe barrier to ensure both were separated but could still see each other. Of course the cat hissed and went downstairs and we corrected the puppy to leave her alone. The cat remained downstairs for a few days, then started to venture up. We always made sure the puppy didn’t think the cat was a play toy and soon she was comfortable with him being in the home. We kept the gate up for months, so that way the cat always had a safe place to be without the pup. We eventually moved the gate to our laundry room and this is where her litterbox and food stays. Cats can do some harm to a little pup so always make sure they have an escape route, and a safe room they can call their own.