How to Bring a Second Cat Into the Family and Not Make Your Old Cat Upset

Three Methods:Preparing to Introduce a New Cat to Your HomeIntroducing the CatsDealing with Aggression

Cats have complex personalities, and it is not possible to know how any given cat will react to another animal of any kind. Sometimes, two cats are not compatible. However, it is possible to take measures in order to prevent and/or minimize potential negative emotions. Many cats live harmoniously together, especially when you ease them into new social contexts. Make sure you take the time and care to properly introduce your cats, so that you foster their good relations.

Method 1
Preparing to Introduce a New Cat to Your Home

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    Give your cats enough time. Both cats will require your love and attention. This means petting them, and also playing with them. Set aside twenty minutes, twice a day to play with your cats. If they can't yet play together, make sure you give them equal time.
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    Be sure there is enough space for your cats. A studio apartment might not be the best place to keep two cats. Adding vertical spaces, like cat towers, can help to give your cats more room. Cats like to be able to create social distance, and too much crowding can stress them out.
    • Cats are naturally territorial. These are natural impulses in cats, and so conflict over territory is to be expected, though not guaranteed.[1]
    • About 19 square feet of floor per cat is recommended when housing multiple cats.
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    Have one litter box per cat, plus one spare. This means two cats require three boxes. This is to make sure your cats feel comfortable. If one cat feels the litter box is the other cat's territory, they may be likely to go to the bathroom somewhere else. Avoid the mess and ease your cats' stress levels by giving them each a litter box.
    • Keep a litter box on each floor of your house if you have more than one floor.
    • Make sure there is at least three feet between the litter box and food dishes.
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    Make sure your cats each have their own water and food dish. If your cats have to eat from the same food dish, this might cause undue aggression. Having a food and water dish per cat will also help you to be certain each cat is eating well. Sometimes one cat will eat all the other's food.
    • Don't feed your cats too close together, or it might cause them to fight.
    • Especially when your new cat first arrives, place food dishes on opposite sides of the room, or opposite sides of a closed door.
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    Own one carrier/crate for each cat. This is essential not just for transporting them, but it is also important for limiting their ability to physically contact each other. In the event of an emergency, you will need a carrier for each cat. Also, it can help both cats feel like they have a space of their own to hide in, increases their sense of safety.

Method 2
Introducing the Cats

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    Keep cats separate at first. Try not to let your cats even come into contact on their first few days. Put the newcomer in a small room by themselves. They will more comfortable in the smaller confines, and they will be unable to come into contact with your current cat. Start by doing this for seven days.[2]
    • This is a slow acclimation process, and you may have to repeat it.
    • Don't ignore your old cat when you get a new cat. This can cause your old cat to hate the new cat and feel sad.
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    Introduce them by smell. Allow the cats to smell each other under a door, but do not let them have physical contact. Bring toys or bedding that both cats use to allow the other to become accustomed to the new scent. This will help the cats get used to the idea that there is another cat around.
    • Help your new cat to acclimate to the scent of the old cat using footwear. After a couple days have gone by, rub a small clothing item (such as a sock) all over the old cat, to pick up its scent. Then place it in with the new cat. Watch the reaction. Hissing is normal, but if the new cat is okay with the old-cat-scented sock, praise the new cat and give it a treat.
    • Some behaviorists suggest rubbing the cats separately with the same towel to intermix their scents. First gently rub one cat with the towel. Then rub the other cat. After the towel carries both cats’ scents, bring the towel back to the first cat and rub her with it again [3]
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    Introduce them by sight. Don't let them come into physical contact. A child or doggy gate will work to separate them in this case. Watch how they interact. Does their body language indicate distress, or do they seem calm and accepting of the other? These signs will inform you as to how long the process should take. Calm, friendly cats do not require as long of an acclimation process as ones who exhibit aggression.
    • Stack two baby gates on top of each other in the doorway to the new cat's room, to ensure neither cat can get to the other.
    • Let your old cat discover the new cat in the room on its own.
    • If they both have non-aggressive reactions, praise them and give them a treat. If not, shut the door and try again some other time
    • Keep the gates up for a while. You can leave the baby gates up and the two can meet and greet as they please.
    • Watch for defensive postures
      • Crouching
      • Head tucked in
      • Tail curved around the body and tucked in
      • Eyes wide open with pupils partially or fully dilated
      • Ears flattened sideways or backward on the head
      • Piloerection (hackles up/hair stands on end)
      • Turning sideways to the opponent, not straight on
      • Open-mouthed hissing or spitting
      • Might deliver quick strikes with front paws, claws out
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    Switch their positions. After some time, place your old cat in the room where you kept the new cat, and let the new cat explore its new home. This will let your old cat examine all the smells and the space of the new cat, and it will give the new cat a chance to be more comfortable in the new space you provide. Do this a couple times, before proceeding in the acclimation process.[4]
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    Allow them to interact. Once they've had time to adequately acclimate to the new situation, let them come into contact with each other. Keep a spray bottle handy, in case of aggression. If your cats get along fine, you may be ready to let them both roam free. Even still, pay close attention to their behavior. The key to having a multi-cat household is preventing territorial aggression.[5]
    • Place them both in a room where you can supervise.
    • Only allow them about ten minutes or so for the first meeting. You can gradually increase it as the days go on, but you don't want them to become agitated.
    • Introductions can take weeks, or they can take months. The important thing to remember is to go at the cats' pace. It may be slow, but it's worth it if your cats will live together in peace.
    • Never physically punish your cat(s) for something like hissing or fighting with each other. This is a very common reaction. If one cat starts being aggressive pick the other cat up instead. And always make sure they are not just play fighting, these can be hard to tell apart.
    • Watch for offensive postures.
      • A stiff, straight-legged upright stance
      • Stiffened rear legs, with the rear end raised and the back sloped downward toward the head
      • Tail is held straight and stiff, like a classic Halloween cat's posture
      • Direct stare
      • Upright ears, with the backs rotated slightly forward
      • Piloerection (hackles up), including fur on the tail
      • Constricted pupils
      • Directly facing opponent, possibly moving toward him
      • Might be growling, howling or yowling
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    Feed them around each other. When cats are eating from a bowl of food, they are in a non-aggressive state. By feeding them together, even across the room from each other, they get used to being non-aggressive when the other is present. Treats when both cats are calmly together can also help to reinforce good behavior.
    • Every time the cats see each other, give them treats. They will associate "treat time" with each other and feel the positive benefits of being around each other. It also shows them that they don't have to compete for food or attention, and that enough is provided for both of them.
    • If the cats won't eat, or become aggressive, they are probably too close together.
    • If they eat and seem relaxed, they can be moved closer together at the next feeding session.
    • This whole process can take weeks or even months. Signs of anxiety or aggression usually indicate that the introductions are proceeding too quickly. Address signs of outward aggression:
      • Swatting, striking with paws
      • Biting
      • Fighting
      • Growling, shrieking
      • Scratching
      • Preparing for an all-out attack by rolling onto side or back and exposing teeth and claws.[6]

Method 3
Dealing with Aggression

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    Know that there are many ways in which cat aggression manifests. Cats are complex, and not fully understood. But what we do know is that there are a number of distinct patterns of involved with cat aggression. These can be broken into a series of situation-oriented categories that are not mutually exclusive.[7]
    • Play aggression happens when cats take play too far.
    • Fear/Defense aggression comes from the cat feeling endangered, possibly irrationally.
    • Territorial aggression is usually just among cats, but can be expressed toward humans and other animals.
    • Petting aggression is not well understood, and may come from over-stimulation.
    • Inter-Male aggression relies on the natural competitive nature between toms.
    • Maternal aggression is the queen cat's instinctual protective response.
    • Redirected aggression can come from frustration the cat cannot vent, which get redirected toward another target, such as a nearby cat or person.
    • Predatory aggression derives from cats who predatory instincts are triggered.
    • Pain aggression results from old or current sensations of pain either from illness or trauma.
    • Idiopathic aggression is spontaneous, and may be a threat to the physical safety of those who come into contact with the cat.
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    Contain, limit, or restrict them if there is aggression. It is very important to deal with aggression among cats. Cats do not work out their problems with fighting. In cases with extended aggression, it may be necessary to limit or control the cat's the in each other's presence. This is so that they become accustomed to being in a non-aggressive state when the other is near. Make sure you are prepared to do this if either of your cats become consistently aggressive.
    • Have room set up with food, water, a litter tray, and cat bed, and put the newest cat in there, as a form of time-out, to let the tension decrease.
    • Use a leash or harness. This can give your cats more freedom, while still limiting their access to each other.
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    Get medication. If the cats still cannot get along, your veterinarian may prescribe medication for both. Keep in mind that medication is only part of the solution, and your veterinarian may be reluctant to prescribe it before checking you have explored all behavioral options for introducing the cats to each other correctly. Medications are not a magic bullet. It must be used in conjunction with slow introductions and consistent rewards for peaceful behavior. Use medication as a last resort.[8]
    • Benzodiazepines are sometimes used when cats are fearful or aggressive in a highly reactive way. However, benzodiazepines reduce the cat's ability to learn, which makes it harder to teach the cat's to get along.
    • Tricyclic antidepressants can be used in case where there is extended conflict in multiple cat homes.
    • Monoamine oxidase inhibitors (MAOI) work on similar neurotransmitters as Tricyclic antidepressants, but they work differently and with less selectivity, so they have a more general effect on the brain.[9]


  • Know each cat is different. Cats are complicated animals. Personality can vary by breed and by individual. Don't be surprised if your cat acts in an unexpected way.
  • When the cats start to get used to each other, start letting them take turns playing with a toy.
  • Make sure your new cat has been tested and is free of Feline Leukemia (FeLV), FIV, and Feline AIDS prior to introducing him to your old cat.
  • Cat trees can be a godsend, and you'll notice that your cats will appreciate having more vertical territory, if you can't expand horizontally. It also may help cut down on aggression.
  • If they lick each other, or show any signs of affection with each other, give them each a treat to reward them.
  • It helps if both of them are kittens, or if the new cat is a kitten. Your old cat is more likely to accept a younger cat than an older one.


  • Sometimes your old cat will still hate the new arrival.
  • Some cats can be so aggressive that it may be necessary to re-house them.

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Categories: Getting a Cat