Step 1: Set up a “base camp” for your new cat. This can be a bathroom or a spare bedroom - any room with a door that closes and minimal places to hide. It should include their litter box, toys, and surfaces that hold their scent like scratchers, blankets or beds.
Step 2: Once your new cat has settled into their base camp, you can start site swapping. The new cat gets to explore the rest of the house while the resident cat gets to explore the new cat’s base camp. This allows both cats to start to get to know each other through scent first!
Step 3: STart mealtime introductions. Place each cat’s food bowl a few feet back from the closed door. This method allows them to smell each other while associating the smell with something good, FOOD! Move the bowls closer and closer to the door with each feeding until the bowls are against the door. If the cats exhibit growling, hissing, or avoidance, back the bowl up to where these behaviors stop.
Step 4: Graduate to a baby gate. Use a baby gate with a towel draped over it so that there is a 1-2 inch gap at the bottom of the gate for cats to see each other. Back the bowls up again to a few feet from either side of the gate. At each meal, raise the towel a little and slowly start moving the bowls closer to the gate until the gate is completely uncovered and the bowls are on either side of the gate.
Step 5: Introduce them in the same room, but make sure they have something to do! Keep both cats occupied with either food, play, brushing, or human affection. If they start staring at each other, distract them. If distraction doesn’t work, separate them.