Are You and Your Current Cat Ready?

Before bringing a second pet home: 

• Follow the 3-3-3 Rule, to ensure your current cat has had enough time to adjust and decompress. Make sure you have had your current cat for longer than three months, and they are acclimated, comfortable and relaxed at home. (For more information, check out: Adopting: The Rule of 3s.)
• Assess your resident cat(s). Before bringing a new pet home, assess whether or not this will enrich your current cat’s life and increase their overall quality of life. If your cat has not been able to live comfortably with other animals in the past — due to their behavior, tolerance threshold or sociability — getting a second pet could be challenging, stressful and even detrimental to your cat's emotional well-being. 
• Is your resident cat healthy and happy? Consider taking your current cat to the vet to make sure they are not experiencing any medical issues, contagious illnesses or physical pain. If your current cat is dealing with any of these things, they are likely experiencing heightened stress and are more susceptible to trigger stacking (For more information, check out: Trigger Stacking & Stress Hormones and Stressed Out: How You Can Tell and What You Can Do About It). Bring in another cat only if your current cat is healthy and their behavioral and emotional needs are being met. 
• Do you have the appropriate set up? To successfully introduce cats in the home, you will need to keep them completely separate for the first few weeks. The new cat will need to be set up in a safe space (in a separate room or part of the home) where the other cat cannot get to them. Consider getting exercise pens or baby gates to use as barriers when it comes time to start introductions. Additionally, slow introductions take time, supervision and patience. Are you (or other family members) able to supervise all interactions between the two cats for the first few months? Are you willing and able to take on training if the two cats aren't comfortable with each other right away? For more information on safe spaces, see the "Preparation" section below.

Your cat may be a good candidate for having a roommate, if:

• Your cat has successfully shared space with or lived with cats, in the past. 
• Your cat is generally social, friendly and gentle with other animals or cats. 
• Your cat is generally confident, mellow and easy-going.
• Your cat does not have any current behavior challenges that may be exacerbated by a second pet, including: litter box issues, spraying, or fearful behavior.
• Your cat does not guard resources (food, cat trees, treats, scratchers, toys, beds, people, etc.) from other animals by tensing, freezing, hissing, swatting, spraying or biting.
• If your cat does show resource guarding behaviors, it's to a degree that is preventable and easily managed (For more information, check out our YouTube playlist: Resource Guarding Resources).
• Please note: When assessing a cat's behavior and personality, be careful not to assign rigid labels to them. Behavior changes in different contexts. Labels can be helpful when describing and understanding our pets' behavior, but they shouldn't define who your pet is. It's important to keep in mind, an animal's behavior is influenced by their environment. Ask yourself: What is my cat doing and under what conditions? (For more information on why cats do what they do, check out: How Behavior Works: Learning Theory & Training Methods, How Cats Learn and Why Animals Do What They Do.)

For more things to consider, check out these resources: Introducing Dogs & Cats, Adopting: Cats & Kittens and Introducing Dogs At Home.

Finding a Prospective Cat

For additional tips on how to find the right pet for you, check out our Behavior & Training Lecture: Adopting/Transitioning Shelter Pets.

• Behavioral History: Find out as much as you can about the behavioral history of any cat you are considering adopting, specifically in regard to living with other cats. Ideally, the new cat you plan to bring home will have a history of having lived comfortably with other cats, without apparent conflict. Avoid adopting a cat that has a history of fights with other cats, harm to another cat, or extreme shyness or fearfulness (Check out the article, Adopting A Cat: Things To Consider, for more tips on how to find the right cat for you). 
• Confidence is key. Look for a confident and easy going cat or kitten. Relaxed and confident cats are more likely to adjust comfortably to living with another pet. Confident cats are less likely to be overly stressed, threatened or otherwise negatively impacted by sharing a home with another cat. On the other hand, shy, fearful and declawed cats may feel vulnerable and stressed sharing a space with other cats. Stress in cats can have serious negative effects such as lack of appetite, litter box issues, and higher risk of illnesses (For more information, check out the article, Stress in Pets: What To Look For).
• Make it easy for your current resident cat. If your current cat is shy, nervous or sensitive, look for a cat who is especially soft, gentle and mellow, yet still easy-going and relatively confident (For additional tips for shy cats, check out: Shy & Fearful Cat Tips. Enroll in our Shy Cat class). If your current cat often comes on strong, is high energy or is easily overstimulated and frustrated, look for a cat who is especially outgoing, sturdy and high energy (For additional tips for energetic or overstimulated cats, check out: Overexcited & Energetic Cat Tips, How to Socialize an Overstimulated Cat and Excessive Meowing. Enroll in our The Trainable Cat: Level 1 class).
• Sociable and well-socialized: Look for a cat who is either tolerant of or social towards other cats — sociability is a spectrum. Additionally, look for a cat who has been socialized to other cats at an early age. If a cat wasn’t socialized to other animals at a young age, they are less likely to show appropriate, relaxed or “neutral” behaviors toward other cats as an adult. (For socialization tips, check out our YouTube playlist: Well-Socialized Pet Resources. Enroll in all 6 of our free Well-Socialized Pet Chats held live online over Zoom.)
• Slow introductions! Regardless of whether you have information about a cat’s history with other animals or you’re bringing home a young kitten, you’ll want to gradually introduce your current cat(s) to your new cat. It's important to go at your cats' pace to avoid rushing the introductions. Read their body language, listen to their stress signals and pay attention to their comfort levels. They will tell you when they are ready for the next step in the introduction process. The number one rule: Go slow. When in doubt, slow down. For more information and a step-by-step of the process, see the "Slow Introduction Process" section below.
• Check out our YouTube playlist: Impulse Control, Overstimulation, DSCC & Choice.

Preparation

• Set up a safe space for the new cat: Before bringing home another cat, set up a room to be the new cat's safe space. This needs to be a closed off area with a door that your other cat cannot access. It is important to keep the cats completely separate for the first week or so. When the new cat is in the safe space, they should not be able to see each other. The safe room should have everything your cat needs: food, water, their own litter box separate from the resident cat's, places to hide, multiple scratchers (offer a variety), places to rest and sleep, and toys and enrichment. This will be the room your new cat will stay in for the first few weeks while they are adjusting to the new home and family, before meeting the resident cat and gaining access to the rest of the home. The safe space will be important during the introduction process. Utilize baby gates or ex-pens so your resident cat cannot get too close to the safe space (For more information on how to set up a safe room and the importance of one, check out: Cat Confinement in a New Home and Adopting: Shy & Fearful Cats.)
• Double the cats, Double the resources...Double the fun! You may be thinking you don't need to get more cat supplies, since you already have a cat and lots of cat stuff. While most cats can share toys, beds, scratchers and cat trees, it's best to provide an abundance of resources. We don't want the cats to feel like they have to fight for resources. Furthermore, cats are sensitive to smells and can be territorial. Provide each cat with their own beds so they can have a place to relax that feels like their own. Of course, they may end up sharing beds, trading beds, or even sleeping in the same bed together. Provide a variety of different types of scratchers in different areas of the home. This will reduce the risk of inappropriate scratching. Additionally, you are going to want to get your new cat their own food bowl, water bowl and litter box. This will reduce the risk of resource guarding or appetite issues. This is especially necessary for the first few months, while the new cat is living in their safe space. However, it will still be necessary when the cats are sharing the same space. The Litter Box Golden Rule: one for each cat, plus an extra! This will help reduce the risk of litter box issues or inappropriate elimination. 
• Escape Options: Provide both cats with options to escape from each other and retreat to for alone time. Make sure there is an abundance of hiding places and high up spaces (cat shelves, cat trees, cubbies, cat walls, etc.) for both cats to enjoy, so they don't feel the need to fight over them. Once it comes time for the cats to interact, it's important they have ample hiding spots and escape options that are easy for them to access. If your cats feel they can't get away from each other, they may feel threatened and resort to swatting, scratching, fighting or biting.
• Plan Ahead: Create a plan for when the new cat arrives home. Put your current cat away in a closed room or another area of the home before bringing the new cat inside to their safe space. Offer the resident cat a puzzle toy, licky mat or other form of enrichment to help them relax and stay busy. Then, bring the new cat inside straight to their safe space. Place the cat carrier on the ground and open the door. Let your new cat come out on their own time. Do not let the resident cat explore outside your new cat's safe space. They will smell each other and likely hear each other but they shouldn't be able to "meet" yet, even through a barrier or door. 

Body Language: What to Look For and What to Expect 

The introductory period can take weeks or even months of brief, gradual and supervised introductions. At each stage, observe both cats' body language and behavior to gauge how they are feeling about their new roommate. Only move to the next stage of introductions when both cats appear comfortable and relaxed. For an in-depth presentation on body language, check out: Behavior & Training Lecture: Can You Speak Dog or Cat?

Cats will display a range of behaviors that indicate whether they can comfortably and appropriately share space with another cat. Indications that your cat is experiencing relaxation or positive emotions include a soft, relaxed and "neutral" body, narrowed, soft eyes with constricted (small) pupils, a loose low or softly swishing tail and choosing other behaviors while in the presence of the other cat, such as calmly moving away, grooming, sitting or lying down. Indications that your cat is experiencing stress, overstimulation, fear or other negative emotions include a stiff and alert body, tense facial muscles, showing teeth, wide eyes with dilated (large) pupils, puffed up tail and fur (piloerection), stiff tail vibrating up high or large swishing tail, ears back, and being unable to break focus from the other cat (fixation). Other stress signals and behaviors include swatting and clawing, hissing, yowling, spitting, biting, fleeing, hard stare and fixation (intent focus) and apparent agitation. The goal is calm, relaxed body language and indications of positive emotions towards the other cat. If the cats are not calm, move back a step and slow down. Consistent hiding, changes to or loss of appetite, litter box issues or changes in elimination habits, medical issues like Upper Respiratory Infection (URI) or Urinary Tract Infection (UTI), sudden disinterest in playing and other changes in your cat's behavior may indicate that they are experiencing high levels of stress and are not comfortable sharing space with another cat. (For more information on cat body language, check out this video: Cat Body Language 101.)

Help Your New Cat Settle In

• Let the new cat decompress before starting the introduction process. Remember the 3-3-3 Rule: We want to give the new cat ample time to decompress and become familiar with the household routines before adding the extra stress that comes with introducing cats. They shouldn’t meet face-to-face for several weeks, but they’ll be able to smell and hear each other. During this time, you should do everything you can to help your new cat feel comfortable, safe and stress-free. They will probably want to hide and sleep often. Give your new cat time, space and privacy to relax and come out of their shell.
• Pair your presence with positive things. Whenever you enter your cat's safe room to refill the water bowl, feed meals, scoop the litter box, or initiate play, scatter delicious treats around the room and toss a few to the cat. This will not only help your new cat associate you with good things, but it also provides them with an opportunity to forage for treats. Foraging is a natural species-specific behavior that is calming and enjoyable for cats.
• Consent: To build a trusting relationship with your new cat, let them initiate physical interaction and affection. Let your cat come to you when they are ready. (For more information, check out: What Consent Looks Like in Cats, Study: Letting cats decide when to be petted avoids hostility & increases their affection, and Low Pressure Interactions in a Space
• Pheromone diffusers: Pheromone sprays and diffusers, such as Feliway, can help cats feel more calm and comfortable, especially in a new environment with new, unfamiliar smells. Cats are very sensitive to scent — new smells, the smell of other cats and the lack of their own scent in an environment can cause stress and discomfort. Pheromones provide cats with a calming scent that can reduce signs of stress. There are even "Multi-Cat" pheromone diffusers that can reduce tension and conflict between cats, such as fighting, chasing and blocking.

Integrating a New Cat into Your Fur Family

For additional tips, check out: Behavior & Training Lecture: Introducing New Pets.

• Spend equal time with both pets. You should spend time with each cat separately and allow them to smell their scents on you. Be sure to pay extra attention to the resident cat, so they don’t associate the change and presence of a new cat with less affection and attention. Aim to make positive associations for both pets.
• Create A Shared Scent with Allogrooming: Allogrooming, sometimes referred to as "social grooming," is a behavior in which social animals of the same species clean or groom one another. It often happens between cats who are related or very familiar with one another, as it can strengthen social bonds. Allogrooming creates a shared scent between cats, allowing them to view each other as "one of their own," rather than an "outsider" and potential threat. Cat owners can initiate allogrooming between their cats to promote positive associations with one another and help them start building a social bond. One of the ways we can do this is by brushing both cats with the same brush to create a shared scent, before they meet face-to-face. First brush one cat (Cat A), then brush the other cat (Cat B) with the same brush. Go back to brusing Cat A and then brush Cat B again. Repeat this process but switch up the order, starting with Cat B and ending with Cat A. This ensures that both cats will receive the other cat's scent. 
• Physical Exercise & Mental Enrichment: Be sure that both cats have gotten plenty of mental and physical exercise before meeting, so that they will have burned off some energy. Provide mental enrichment and physical play for the cats, to help them de-stress and avoid overstimulation. Bonus: Interactive play is a great way to engage and bond with your new cat! (For more information on mental enrichment, check out: Enrichment Resources YouTube Playlist, Enrichment: Brain Games for Mental Health and Enrichment: Indoor Activities.) 
• Use the "Cat Activity Cycle" to your advantage: The cat activity cycle — hunt or play, catch, eat, groom, sleep, repeat — is a cat's instinctive routine driven by their internal clock. Similar to how humans' circadian rhythm, or internal biological clock, influences our sleeping and eating patterns, cats have a natural pattern of activities. This activity cycle — also referred to as energy cycle or play cycle — can be used to your advantage when it comes to facilitating cat introductions. Make sure both cats have been played with and fed before starting an introductory session. After engaging in play and then eating, your cats should be more mellow and ready to groom and sleep. Hopefully, this will allow the interaction to be calmer. Also, if both cats are more interested in grooming, they will be less fixated on each other, which is a good thing. The goal is calm and "neutral," not "obsessed" and excited.

•  Follow the cats' lead: It is important to go at your cats' pace, so as to not pressure them to interact or move to the next step in the process before they are ready. Let the animals choose to interact on their own terms (Check out: Social Pressure & Animal Interactions and The Importance of Choice in Animal Training). You may be wondering, "How do I know if my cats are ready to move forward with the introduction?" Observe and read both cats' body language throughout the process, and only move to the next step when both cats are comfortable.Your cats are ready for the next step if they are both feeling good and comfortable. Signs your cat is feeling good include showing calm behavior and body language, able to relax in the presence of the other pet or the other cat's sounds and scent, enthusiastically taking treats and interacting with the other cat, not showing signs of stress, being shut down or feeling conflicted and not showing signs of overstimulation, overexcitement, frustration or fixation. 

• Safety First: While it can be tempting to skip to the fun and exciting part of the introduction process — face-to-face interaction — it’s crucial to go slow to ensure that your cats will interact safely and appropriately when the time comes. Cats can cause injury if they feel threatened and cat fights are not fun for anyone involved. To minimize the risk of injury to either people or pets, only allow face-to-face interactions when the cats are ready and someone is there to supervise.

• Redirection, Interruption & Initiating Breaks: At all times during animal introductions, make sure you can redirect the animals' attention to another activity if they become frustrated, overstimulated, fearful or fixated. You can use toys, treats and praise so that they’ll focus on you. Interrupt and redirect your cats if they are engaging in direct eye contact, hard staring at the other cat, vocalizing, showing stress, fear or overexcitement behaviors and body language, playing too rough for too long, or are not taking breaks (Check out these videos: How to use your voice as a training tool and Eye Contact & Animal Interactions). The goal is for both pets to be able to take frequent breaks and check in with each other on their own (Check out this video: Check ins). However, many pets need human intervention to take breaks and be redirected to more appropriate activities. For an example of a play attempt between cats, check out this video: Ginny & Poe early play attempts.
• Freedom to Flee: DO NOT force the cats into each other's space by holding them, caging them or otherwise restricting their ability to escape. The cats need to be able to flee at any time. If an animal feels trapped or pressured to interact, they will form negative feelings about the other animal. 
• Decompress & Regress: If the cats get into a scuffle, you’ll want to completely separate them again so they are unable to interact or see each other. Inspect both cats for any sign of injury or pain. Spend time with each of them individually. Allow time for them to decompress from the stressful and unpleasant event. Wait 3-6 days and then begin the integration process again, but this time much slower. You may need to regress and go back a step in the process for a fresh start. If there are clumps of fur left behind after the scuffle, this indicates it was a more serious fight. Consider reaching out to a trainer if this happens.
• Patience & Vigilance: In the first few weeks, observe whether things are getting better or worse. You may have to stay on one step for a while, repeat steps or go back a step if your cats are not comfortable. There is no universal timeline, it depends on the individual animals. The integration process can take a long time, and it can also be stressful and frustrating. Be patient and continue to monitor their interactions until there is a pattern or plateau in their relationship. Most cats will adjust to living within a multi-cat household. Like people, some will enjoy it more than others. Patience is the most important factor to ensuring you’ll have harmony in your home.
• For more information on sociability and animal interactions: Check out our YouTube playlist on Sociability, Reactivity, Leash Skills & Play.

Slow Introduction Process

1. Complete Separation: You will want to keep the cats completely separated without access to each other for at least a week to give your new cat time to settle in before beginning the slow introduction process. Additionally, be sure that the resident cat does not have access to the area right outside the new cat’s safe space. We DO NOT want them interacting through the door yet. Set up ex-pens or baby gates outside of the new cat's safe space or keep the other cat in a separate part of the home, when unsupervised. This will ensure the resident cat is not hanging around outside the new cat’s safe room. During this time they will hear and smell each other, but should not be able to see each other or interact. 
2. Scent Swapping: During that time of complete separation, we can start building enthusiasm through scent swapping. When scent swapping, we want to start with exposing the cats to each other’s scent only for short periods of time. Present a blanket or toy with the other cat's scent and be ready with treats to reward their calm behavior when the other cat’s smell is present. This will start creating positive associations with the other cat. Ideally, we would remove the scented object from both cats BEFORE they have a chance to react negatively towards it. So, immediately start rewarding any interaction your cat has with the scented object (looking at, smelling it, touching it, laying on it) and then remove the object after some time. Don’t leave the scented object with either cat. At the beginning, we only want the scent present if someone is also present to reward the cats with treats. Over time you can extend the length of time the scented object is present. Eventually, you can leave the scented object with your cats for long periods of time, but only if they have showed calm behavior with it. Once you are able to observe consistent calm, relaxed behavior from BOTH cats while scent swapping, you can move on to Step 3.
3. Through a barrier (door): You will need two people for this step of the introductions. Have one person in the safe room with the new cat and the other outside the room with the resident cat. Start by feeding or treating both cats on either side of the door. Keep these sessions short, and always end on a good note before either cat becomes stressed, frustrated or overstimulated. If either of the cats start showing signs they are uncomfortable or fixated, stop and call both of them away from the door. You can lure with treats or a toy. End the session before it can escalate. Once both cats are comfortable with this step (no hissing, yowling, spitting or growling, no puffed fur, no swatting, relaxed body language, etc.), then you can move to the next step.
4. Through a see-through barrier (baby gate, ex-pen, glass door, cracked open door): Once both cats are less interested in each other and they are comfortable interacting through the closed door, you can begin planning for them to meet through a see-through barrier. You can use a baby gate, ex-pen or glass door, or crack open the door to the safe space just enough for them to see each other. Once again, you will need two people for this step. Have someone on one side of the barrier with the new cat and someone on the other side with the resident cat. Repeat Step 3 while allowing the cats to see each other and being given treats. They should be able to see each other but not fully get to each other. Allow the cats to approach the barrier on their own, do not force them. If they behave in a relaxed and/or cautious way, try not to intervene in their interactions except to praise and reward them for appropriate behavior. If either of them is not calm, redirect them and interrupt any negative interactions that may be happening (staring, vocalizing, swatting, lunging etc.). Keep this session very short and end before it can escalate. Once both cats are comfortable with this step (no hissing, yowling, spitting, or growling, no puffed fur, no swatting, relaxed body language, etc.), then you can move to the next step.
5. Open the safe space door: When you’re ready for face-to-face interactions, create a plan and prepare the area. You should only move to this final step, when both cats are ready. They have to show you (with their body language) that they are both comfortable with the previous steps. If they were not and you still push forward to this step, you risk them getting into a fight or building negative associations with each other. You will need two people for this step, one person to work with each cat. Keep the resident cat away from the safe space, preferably in a completely other area of the home. We do not want them rushing up to the new cat, when they leave the safe space. Open the door to the safe space and allow the cat to venture out on their own time. Treat and praise both cats to continue building positive associations with one another (For more information, check out: Counter Conditioning and Positive Reinforcement). 
6. Controlled, supervised in-person meeting: Arm yourselves with lots of treats and do this in a large area of the home with lots of space for the cats to run and hide from each other if need be. We don’t want them to feel confined or pressured to interact. Each person should have a wand toy to use as redirection, if needed. As soon as the new cat begins to enter an area where the other cat is present, start rewarding both cats with praise, treats, toys, etc. Try to keep a little bit of space between the two cats using redirection. Only allow them to approach each other and get close to each other if they both are calm and comfortable with it. Reward both cats for looking at each other AND for looking away from each other (see infographic: The Engage-Disengage Game). If either of them is not calm, redirect them and interrupt any negative interactions that may be happening (staring, vocalizing, swatting, crouching, lunging etc.). Keep this session very short and end before it can escalate. Repeat this step many times, gradually extending the length of the sessions, before letting them interact unsupervised or for long periods of time. (For more information, check out: How Animals Learn & Why Behavior Works YouTube Playlist.)

Ask For Help

If, for whatever reason, things are not working out, San Diego Humane Society is here to help. We understand that being a pet parent can be challenging — especially with multiple pets — which is why we offer numerous options and resources for pet parents in need.

If your cats are not getting along, here are your options:

1. Completely separate them, for safety. Restart the slow introduction process from the very beginning.
2. If you adopted one or both of your cats from San Diego Humane Society, you are provided with a cost-free, 1-hour Post Adoption Consultation online over Zoom. One of our Community Animal Trainers will help troubleshoot while providing starting points and next steps for you. Book here: Schedule a Post Adoption Consultation.
3. Contact our Behavior & Training Helpline, available for all community members, whether you adopted your pet from San Diego Humane Society or not.
4. Book an online Private Lesson (1 hour, online over Zoom), for advice and training exercises from one of our Community Animal Trainers. Open to all community members, these sessions focus on environmental management, troubleshooting and training exercises. 
5. Find a positive reinforcement trainer that can come to your home to assess the situation. Find a trainer here: Local Positive Reinforcement Animal Trainer Directory. For additional help finding a trainer, check out: How To Pick A Trainer 101 and Trainer Danger: How To Find A Trainer Who Won't Harm Your Pet.
6. Consider the well-being and quality of life for all animals and humans involved. If needed, rehome your pet here: Give Up/Rehome A Pet here.