Basic education

How to Introduce a Third Cat into a Home

Laura García Ortiz
By Laura García Ortiz, Veterinarian specialized in feline medicine. December 29, 2020
How to Introduce a Third Cat into a Home

See files for Cats

If we love cats, the idea of having many in our home might seem like a dream. However, overcrowding of pets is a problem for everyone involved, especially the animals. The problem is not only to do with the number of animals in a home. We also need to consider space, resources, hygiene and more. Even if we meet the requirements, we can't simply put two or more animals together and assume they will get along. We need to introduce them properly.

At AnimalWised, we ask is adding a third cat a good idea and find out how to introduce a third cat to a home if we decide it is. We do this by providing some guidelines for introducing a third cat.

You may also be interested in: How to Introduce a New Cat to Another Cat
  1. Is adding a third cat a good idea?
  2. Introducing a baby kitten
  3. Introducing an adult cat
  4. Guidelines for introducing a third cat into the home
  5. What to do if the cats do not accept a third cat?

Is adding a third cat a good idea?

Before introducing a new cat into a home with other cats, we need to decide if it is the right decision. The first thing we need to consider are the practical repercussions. You can have too many cats in an apartment, but this depends on the individual circumstances. For this reason, there are some questions we should ask ourselves:

  • Do we have the space for a third cat?
  • Do we have the money and resources to provide for their well-being?
  • Does everyone in the home agree to having a new cat?

If we answer affirmatively to these questions, then we need to consider the cats which currently live in our home. Having two cats together can be a great idea as they provide companionship to each other. If they arrived together and were from the same litter, then they should know each other well enough to get along in a new environment.

When we introduce a new cat to another, there are certain considerations to make. When we are trying to add a third to a pair of cats, there are other specific issues we need to consider. Even when two cats live with each other, their relationship can vary considerably. Some may get along very well, others tolerate each other, but don't interact much, and some may even fight.

We not only need to consider the personality of the cats which live there, but also the personality of the third cat we introduce. This is not something which is easy to do. If we adopt a cat from a shelter, we need to know how they have behaved up to that point. The shelter staff should be able to tell you whether or not they get along with other cats.

Since cats are territorial animals, it is likely the two cats which live there already will be more dominant in the relationship since they have the home-turf advantage. However, this can change depending on the temperament of the new animal. This is why we need to do what we can to make introduction go smoothly.

Introducing a baby kitten

When the third cat is a kitten, their introduction is usually easier. A kitten is usually learning how to understand their environment, so bring them into a new one will often means they will be able to adapt better. If the cats we have in the home are also kittens, they should be able to grow up together fairly easily.

For adult cats, it is not uncommon to hiss at the kitten new arrival. This is normal as they may see the kitten as a threat to their resources, especially their territory and freedom. However, within a few days, they should recognize the kitten represents little to no threat. This is less likely to happen if the adult cat is not well-socialized.

Some adult cats might feel harassed by a kitten since the little one will likely want to play. Although adult cats play also, they don't do so to the degree of kittens which use play as a way to explore their environment. The kitten will often take any opportunity to invite them to play. This can be bothersome, especially to cats which have a quiet routine.

It is also possible the cats will have a protective instinct over the new kitten. They may enjoy the company and respond well to their energy levels. As always, it will depend on the individuals involved. We also need to provide specific care for the kitten which differs from that of an adult cat.

How to Introduce a Third Cat into a Home - Introducing a baby kitten

Introducing an adult cat

Introducing a third cat which is an adult might be a little trickier. Each cat will have their own personality which has been molded via different factors, including their experiences and development up to that point. This doesn't mean they won't get along, but it does mean it will usually take more time.

Patience and calm are necessary if we want the introduction to go well. There are also practical feline issues which need to be considered. When we bring a new cat into the home, we need to ensure they don't also bring any disease with them. The new cat needs to be tested for retroviruses such as feline immunodeficiency virus and panleukopenia. These diseases are very contagious.

When introducing a third cat to the other two, we need to do it slowly and carefully. This helps to minimize stress, reduce the likelihood of confrontation and find the best way to achieve harmony. Some people may claim you can just put the new cat in the same place and ‘see what happens’. Even if this works, it may be a tough process.

It will be much better to introduce them slowly and do what we can to make the transition as smooth as possible. We should also ensure the adult cat is neutered. We also need to consider the sex of the cat as this can cause problems for the cats already in the home.

Guidelines for introducing a third cat into the home

Once it has been verified that all the cats are healthy and we have done what we can to relax the atmosphere, the introduction can begin. This is a process which will consist of three stages: isolating the new cat, presenting them in a carrier and final direct contact.

Keep the new cat in a separate room

A new cat entering the home means they enter unfamiliar territory. Not only that, but it is occupied territory. To avoid conflicts with the locals, we need to isolate the cat in a separate room for the first few days. Before direct contact can happen, we can allow the cat to get used to their new surroundings.

The newcomer and the prior residents will be also be able to smell each other. This is important since it gives them prior warning. Also in terms of smell, we can use synthetic pheromones to help the cats feel relaxed in the home when a new animal arrives. It will both help them to be calm as well as associate the new cat with positivity.

We can put toys, beds, food, water and everything they need in the new room. This helps to build security as they will know all their basic care needs are met. We can also bring in items which have the other cats' scents on them. This will help the newcomer be familiar without having met directly.

Presenting in carrier

After the new cat has been in the room for a day or two, we can move on to the next stage of introduction. By placing the new cat in a carrier and then placing the carrier in the same room as the other cats, they can be more aware of each other. We should place them a little higher than the floor, but allow the other cats to see.

In this situation, there are usually two main types of reaction. Either the cats don't show much interest or they will react acutely. In the former case, it is most likely they will adapt well to the new home without much trouble from the current residents. In cases of aggression, we need to prepare for possible trouble.

A good way to help the cats relate to each other positively is to put the carrier near some treats for the cats. This includes food, toys and other things they enjoy. By doing so, you can use positive reinforcement to ensure the cats associate the newcomer with positive experiences. Once toleration grows, you can try feeding them at the same time with the cat still in the carrier. This way they know they will still have the things they need, despite the presence of this new cat.

Direct contact

When we see the cats have tolerated the newcomer more in their carrier, it is time to move on to direct contact. If the cats are calm, we can pick the newcomer up and hold them in the same room as the other cats. They should see that we are protecting the cat. If the cats love and trust us, it will help to associate the new cat with something positive.

While we need to be careful the cats don't start to attack either each other or us, we can act as a mediator for the introduction. We can also reward them when they behave themselves. Speak in a calming voice and don't be stressed. The cats can pick up on our nervousness and respond negatively.

Even with cats which are well-balanced, it is likely there will be some hissing involved. The cats will be defending their territory and showing they are not to be messed with. We will need to tolerate a certain level of this. However, if they are using too much aggression, we will need to take them away.

Some cats simply do not get on well with other cats. Read our article on how to help them get along to learn more.

How to Introduce a Third Cat into a Home - Guidelines for introducing a third cat into the home

What to do if the cats do not accept a third cat?

How long it takes for a new cat to be accepted is not something we can determined beforehand. There are too many variables and each cat is an individual. Some cats will be best friends in days, others can take months to fully get used to each other.

Unfortunately, there are some cases when the cats simply won't get along. If you have not been able to introduce them properly, it is very difficult to work retroactively. This is why it is vital we know as much as we can before we adopt a cat into our home. In these cases it is very difficult to make cats which don't get along change their ways. In fact, it is likely you will need to access the services of a feline ethologist. This is a professional cat behaviorist who can analyze the different personalities of the cats and use their experience to help them best get along.

There are some things you can do before an ethologist gets involved. You can learn more by checking out our video below:

If you want to read similar articles to How to Introduce a Third Cat into a Home, we recommend you visit our Basic education category.

  • R. Álvarez. (2020). Feline Ethology: Basic Guide to Cat Behavior. Amazing Books SL
  • N. Magno. (2017). The language of the cat . Dve publishing.
  • MF Fradin. (2017). Living with your cat . Editorial de Vecchi, SAU
  • GEMFE AVEPA. How to introduce new cats and dogs to your pet . Available at:
Write a comment
Add an image
Click to attach a photo related to your comment
What did you think of this article?
1 of 3
How to Introduce a Third Cat into a Home