How To Introduce Cats the Right Way

By Hannah Hart, DVM on Nov. 1, 2023

two cats lying close together on a chair

How cats are introduced impacts both their mental and physical well-being. Slow, methodical introductions allow cats the highest chance of success in developing a positive relationship that will ensure future peace in the household. In addition, the stress of a strained relationship between cats can negatively impact their health, putting them at greater risk for conditions such as feline lower urinary tract disease (FLUTD) and flare-ups of viral illness.

Here's how to introduce two cats successfully.

Finding the Right Match

Just like with puppies, there is an early socialization period in kittens (2–9 weeks old) when they learn from their mother and siblings how to interact positively with one another. A cat’s experiences during this delicate period in kittenhood can influence how well he gets along with other cats as he grows.

Cats can also have a genetic predisposition toward being either shy or outgoing. Understanding your cat’s genetics and their early life experiences can help you decide if your cat would enjoy having a companion and what personality traits you should focus on when looking for another kitty. For example, a shy cat may need an easygoing companion who will respect your shy cat’s boundaries.

How cats are introduced impacts both their mental and physical well-being.

Age is another factor to consider when choosing an additional cat for the household. Senior cats will usually prefer the company of other senior cats that can match their slower lifestyle, while young cats with a lot of energy may be well-suited to each other.

How To Introduce Cats Step by Step

If your cat did not have much experience with other cats as a kitten, or if your cat’s experiences with other cats as a kitten were not positive, you may need to extend the time spent on each step of the introduction process. This will give your resident cat the best chance of accepting the new cat.

Before getting your new kitty, it may be best to meet with a board-certified veterinary behaviorist or a certified applied animal behavior consultant to evaluate your cat and determine if he is ready to accept another feline.

1. Prep Before the Adoption

There are a few things you can do before the new cat comes home to help increase the chances of the resident cat accepting the new kitty.

A few days before bringing home your new family member, select a room the resident cat does not often use and set it up with the new cat’s things: bedding, cat trees and perches with a view outdoors, toys, food and water bowls, and a litter box.

Ideally, these items will be new, as introducing the resident cat’s scent into the new cat’s environment too early can cause stress. Once the new cat’s room is set up, close the door so the resident cat gets used to the room being inaccessible.

2. Keep the Cats Separated

The day the new cat comes home, take her directly into her new room without allowing any contact with the resident cat. Even visual contact between cats can cause stress and start the relationship off negatively. Allow the new cat time to decompress in her new environment before progressing further in the process.

3. Scent Swap

During the scent-swapping phase, calm, relaxed behavior can be reinforced with treats and praise. Start by allowing the cats to sniff each other from under the closed door. Pay close attention to any negative body language, such as:

Ears flattened against the head
Rigid body posture
Fur standing on end
Bared teeth
Dilated pupils

Positive body language includes:

Ears pointed forward
Loose body posture
Tail straight up in the air or up and slightly curled with the fur flat

When the cats seem relaxed around each other’s scent from under the door, take an item from each of the cats’ environments and place it in the other cat’s environment. This can be a toy, a piece of bedding, or a soft cloth that has been wiped around each cat’s mouth to give each cat a sample of the other’s pheromones.

Once the cats can spend time around each other’s scent items, let them spend about 15 minutes alone in each other’s space. They will still be separated by the door during this time. This exercise allows each cat to grow used to the other’s area in a nonthreatening manner and deposit some of their own scent there.

If your cats remain relaxed, gradually increase the amount of time they spend in each other’s area.

4. Let Them Meet Through a Barrier

Allow the cats to see each other through a barrier, such as a mesh screen between rooms or a baby gate. As before, you can increase the amount of time the cats are able to see each other as long as they both remain calm and relaxed.

5. Remove the Barrier

After the cats seem comfortable with the barrier in place, remove the barrier and allow them brief physical contact. At first, this may be just a few minutes to sniff each other. If there are any signs of aggression, put the barrier back in place and try again another day.

6. Conduct Supervised Playtime

To promote a positive relationship between your cats, engage them in play sessions together, praising and rewarding them for friendly interactions.

Behaviors to reward include gentle mouthing and rubbing against each other, taking turns with dominant and submissive postures, or grooming behaviors that demonstrate that the cats view each other as nonthreatening equals. Take small breaks from playing and grooming behaviors before resuming the interaction.

7. Allow the Cats To Interact Unsupervised

Once the cats have had several supervised play sessions with no signs of aggression, they can begin to spend time together unsupervised.

The best way to ensure success during unsupervised interactions is to provide sufficient resources for each cat. This means:

Multiple cat trees
Plenty of toys and individual attention for each cat
Distinct food and water sources for each cat
One litter box per cat, spaced far enough away to avoid squabbles, plus one extra

It may be helpful to install a camera to observe interactions for the first few days or weeks the cats are allowed to spend unsupervised time together to ensure no fights are occurring in your absence.

Tips for Introducing Cats

Progress slowly and provide ample time for the cats to adjust to each other. This could be days or weeks for any step of the process, so move at their pace. If you notice any signs of stress or aggression, return to the previous step and give the cats more time.
Make use of calming supplements and products to encourage the cats to develop positive feelings toward each other. This can include pheromone diffusers, such as Feliway® Classic, which contains a synthetic version of the feline facial pheromone that promotes positive associations between cats. Another option is Purina®’s Calming Care probiotic powder, which uses a particular strain of gut bacteria to reduce feelings of anxiety. It may also be a good idea to speak with your veterinarian about anti-anxiety medications for your cat, such as fluoxetine.
Closely monitor your cats’ body language when they are interacting. If an issue arises, intervene quickly to prevent injury and reduce the chance of the cats developing hostile feelings toward each other.

It’s important to be realistic when introducing cats. With some, peaceful co-existence may be the goal rather than them becoming friends. However, if you follow these steps and consult with a veterinarian during the process, your cats stand a good chance of developing a harmonious dynamic.

Featured Image: Adobe/Kozioł Kamila