The cat sets the pace, the dog learns the rules
Your dog has had years to learn that home contains no cats, so this introduction is not a single meeting but a retraining of what his home means — and the animal with the least power in any encounter, the cat, must control how fast it moves. Before the animals ever see each other, the cat needs a fully equipped base room: litter tray, food, water, scratching post and high resting spots, behind a door your dog cannot open. If the cat feels trapped at any stage, you go back a step, not forward, however eager or friendly your dog appears.
Stage one: scent before sight
For the first several days the animals only smell each other. Rub a cloth gently on the cat's cheeks and let your dog sniff it for a reward; stroke your dog and leave that bedding near, not in, the cat's room. Feed both animals on opposite sides of the closed base-room door so the other's scent starts to predict meals rather than intrusion. Watch your dog's response to the scent itself: a dog who can sniff, look away and take food calmly is ready for visual contact, while a dog who fixates, whines and scrabbles at the door needs more days at this stage and briefer, better-rewarded sessions.
Stage two: sight at a distance, with an exit the cat owns
Use a sturdy baby gate or a door held slightly ajar and secured, with the cat free to approach or retreat to height at will and your dog on a lead at a distance where he notices the cat but can still turn back to you for food. Sessions stay short — a few minutes of parallel existence, ending while both animals are still relaxed. Reward every look-away, every settle, every moment your dog chooses you over the cat. Any lunging, hard staring you cannot interrupt, or a cat who stops eating or hides for hours afterwards means the distance was too small or the stage came too soon.
Stage three: shared space, still managed
When gate meetings are dull for both animals — and dull is exactly what you want — begin brief shared-room time with your dog on a trailing lead, the cat's escape routes open, and high-value food or resting places removed so there is nothing to contest. Let the cat come and go; never carry her toward the dog for a closer look. Build duration gradually over many sessions, and keep your dog's access to the cat's zones physically blocked between sessions with gates or doors, because one unsupervised chase can undo weeks and genuinely endanger the cat. Many households keep a gate in place permanently, and that is a success, not a failure.
House systems that keep the peace long term
Place litter trays where your dog can never reach them — many dogs eat cat litter and faeces, and a cat ambushed mid-tray will stop trusting the house. Feed the cat up high or behind her gate so she eats unhurried, and give your dog a settled evening place of his own so the cat can cross the room without negotiating with him. Agree with your housemate who supervises which sessions, what the interruption word is, and what either of you does if a chase starts — step on the trailing lead, never grab collars mid-arousal — so both humans respond the same way in the seconds that matter.
One thread for two owners and two animals
Stage plans unravel when one housemate advances a step the other did not know about, or a wobbly session goes unreported and gets repeated the next evening. Keep the introduction plan, each session's outcome and the house rules in a single shared conversation tied to the animals rather than scattered across texts. KinsLe Messenger works well for this because it keeps every conversation about a pet in one per-pet communications hub, so you and your housemate can coordinate the next stage for your dog, and the cat's needs alongside it, from the same thread.