How to Introduce a New Cat to Your Cat or Dog: A Slow, Step-by-Step Plan

The safest way to introduce a new cat is slowly: keep the newcomer in a separate room at first, let the animals get used to each other’s scent, then move to brief sightings and short supervised meetings, only advancing when everyone stays relaxed. Many introductions take one to a few weeks, and some take longer. Rushing is the most common reason introductions go wrong.

Cats are territorial and do not usually welcome a stranger on sight. A first meeting that turns into a chase or a fight can leave both cats wary of each other for a long time, so the goal is to make every early experience boring or pleasant.

Before the new cat comes home

Set up a base room for the newcomer: a spare bedroom, office or bathroom with a door that closes. Put everything the cat needs in it so it never has to cross the resident pets’ territory:

• Food and water bowls, placed away from the litter box
• A litter box with the same type of litter you use elsewhere
• A hiding spot (a covered bed or a cardboard box on its side) and a raised perch
• A scratching post and a few toys
• Bedding you can later swap for scent exchange

Make sure your resident cat keeps all of its usual resources in their usual places. If you are adding a second or third cat, you will also need more litter boxes overall; see our guide to how many litter boxes per cat.

Schedule a vet check for the new cat early, ideally before it has close contact with your other pets, so any parasites or infections can be dealt with first. Your veterinarian can advise how long to keep the cats fully separate for health reasons.

Step-by-step: introducing a new cat to a resident cat

1. Separation (first days). Let the new cat settle in the base room. The cats can hear and smell each other under the door, which is enough at this stage. Spend time with each cat separately.
2. Scent swapping. Once the newcomer is eating and using the litter box normally, swap bedding or a soft cloth between the cats. Place it near, but not on top of, food. You can also gently rub a clean cloth on one cat’s cheeks and leave it in the other cat’s space.
3. Feeding on either side of the door. Feed both cats small meals a few feet from opposite sides of the closed door. If both eat calmly, move the bowls a little closer over several days.
4. Room swaps. Let the new cat explore the rest of the home while the resident cat spends time in the base room. This spreads scent in both directions without a face-to-face meeting.
5. Visual contact. Open the door a crack (secured with a door stopper) or use a tall pet gate or screen door so the cats can see each other during meals or play. Keep sessions short.
6. Short supervised meetings. When both cats look relaxed at the gate, let them share a room for a few minutes with you present. Use play with wand toys and treats to keep things positive. End before anyone gets tense.
7. Gradually longer time together. Extend the sessions over days. Keep the base room available as a retreat, and separate the cats when you are not home until you are confident they get along.

If at any step either cat hisses, growls or stops eating, go back to the previous step for a few days. Going backward is normal and not a failure.

Introducing a cat to a dog

The early steps are the same: a separate base room for the cat, scent swapping and room swaps. The difference is that the dog should be on a leash, or behind a gate, for the first visual meetings.

• Teach or refresh a few cues with the dog first, such as sit, down and leave it, using treats. Our positive reinforcement basics explain how.
• Reward the dog for looking at the cat and then looking back at you, or for lying calmly.
• Make sure the cat always has an escape route and high places the dog cannot reach, such as shelves or a tall cat tree.
• Keep the cat’s food and litter box where the dog cannot get to them.

Some dogs, especially those with a strong drive to chase small animals, may never be safe with a cat unsupervised. If your dog fixates, lunges or will not respond to you around the cat, keep them separated and ask your veterinarian or a certified behaviorist for help.

How long does it take?

There is no fixed schedule. The table below is a rough guide, not a deadline; let the cats set the pace.

Signs it is going well, and warning signs

Positive signs include relaxed postures, slow blinks, tails held up, eating and playing normally, and simply ignoring each other. Our guide to cat body language covers these signals in more detail.

Slow down if you see:

• Hissing, growling or spitting that does not fade within a session
• Flattened ears, a puffed tail, or a low, crouched body
• One cat staring hard at or stalking the other
• A cat that stops eating, hides constantly, or urinates outside the litter box
• Over-grooming or other signs of stress

If a real fight breaks out, do not use your hands to separate the cats. Make a loud noise, or slide a cushion or piece of cardboard between them, then put each in a separate room to calm down and restart the introduction from an earlier step.

When to get professional help

Contact your veterinarian if a cat stops eating for more than a day, stops using the litter box, or seems unwell, because stress can contribute to or mask health problems. If aggression continues after several weeks of careful work, or anyone is getting hurt, ask your vet for a referral to a veterinary behaviorist or certified cat behavior consultant. The Feline Veterinary Medical Association (formerly the AAFP) publishes a free step-by-step introduction guide that is worth reading too.

Bottom line

Give the new cat its own room, let scent do the first introduction, pair every step with food and play, and only move forward when both animals stay calm. A slow start is usually faster in the end than repairing a bad first meeting.

FAQ

Can I just let the cats “work it out”?

It is not recommended. Putting cats together straight away often leads to fear or fighting that can be hard to undo. A gradual introduction is gentler and more reliable.

Is hissing normal during an introduction?

Some hissing early on is common and is a way of saying “give me space.” If it fades as the days pass, things are on track. If it gets worse, slow down.

Are kittens easier to introduce than adult cats?

Often, but not always. A young kitten’s energy can annoy an older cat. Follow the same steps and give the resident cat plenty of quiet places away from the kitten.

What if they never get along?

Some cats only reach a peaceful truce rather than friendship, and that is fine. If there is ongoing fighting or stress-related illness, talk to your veterinarian or a behaviorist about options.