Introducing New Adult Cats

By Catherine Barnette, DVM

Will my current cat readily accept a new cat?

There is no simple answer to this question. In some cases, two laid-back adult cats can be easily introduced with minimal drama. In other cases, however, the introduction does not go as smoothly. Some adult cats may physically fight with each other, resulting in potential injuries. Even in the absence of physical aggression, introductions can provoke anxiety that leads to inappropriate elimination, decreased appetite, or other signs of stress in one or both cats.

Fortunately, you can increase the likelihood of a successful introduction by introducing two adult cats slowly and gradually.

How can I gradually introduce two adult cats?

When you bring your new cat home, set up a small area in which you can confine the new cat. You can use a bathroom, a laundry room, or even a spare bedroom. Set up everything that your new cat will need in this area, including food, water, and a litter box. Allow your new cat to remain in this “safe space” for a few days, until they become more comfortable with their new environment. Visit with both cats (separately) on a regular basis, so you can begin to bond with your new cat while maintaining your bond with your old cat. Your cats may interact under the door during this stage; encourage their interaction if they seem to be playful and interacting positively, but limit access to the door if these interactions appear to be causing distress for either cat.

Once your new cat seems comfortable with the new environment, do a “location swap.” Without allowing your cats to directly interact with each other, allow your old cat to enter the new cat’s space and allow your new cat to explore the rest of your home. This allows your cats to become more familiar with each other’s smells, while also providing your new cat with some time to explore the home. After they have had a couple of hours to explore, return each cat to their own space.

After the two cats have become familiar with each other’s scents through several location swaps, it is time to allow them visual access to each other. You can accomplish this in a number of ways, such as letting them interact through a partially ajar door or opening the door but blocking the opening with baby gates. The goal is to allow the two cats to see each other, but not physically interact, so each cat can become more accustomed to the other’s presence.

If visual interaction is proceeding without any signs of aggression or stress, begin allowing your cats to spend time together. Ideally, this physical introduction should be performed at a time when both cats are distracted. For example, you may want to feed both of the cats near each other or engage both cats in play. Having a distraction can make introductions less intense and provide an outlet for any nervous energy. Remain nearby, so that you can easily separate the cats if either one shows signs of distress. Remember, you are not simply waiting for a fight to break out; you want to pick up on early signs of aggression or stress, so that you can separate the two cats before things escalate. Once things escalate to a fight, it will be much more difficult to start over and teach the cats to like each other!

After your cats have had several successful supervised interactions, you can begin allowing them to interact without direct supervision. Begin with brief periods of unsupervised interaction, gradually allowing your two cats to spend more and more time together.

What should I do if my cats have a negative interaction during these gradual introductions?

If your cats experience a negative interaction (for example, if one cat begins to hiss or growl at the other), return to the last step in the progression that was going well. For example, if hissing or growling began when your cats were allowed visual access to each other, return to interactions under the door and daily “location swapping” to familiarize the cats with each other.

Are there any other tools that might help increase my cats’ likelihood of a successful introduction?

Feline pheromones can help reduce signs of stress in cats. These pheromones are available in both spray and diffuser forms, allowing you to choose a delivery method that works for you. In many cases, the stress reduction provided by pheromones may be enough to relax the cats and facilitate a smoother introduction.

If pheromones alone are not enough, or you are encountering more significant challenges, talk to your veterinarian. Your veterinarian can make behavioral suggestions to help you introduce your cats and can also determine whether your cat may be a candidate for prescription anti-anxiety medication.

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