New Cat? 15 Crucial Warning Signs When Introducing Cats
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Are you thinking about adding a new cat to your feline family?
Before you take the plunge, it’s important to understand that introducing cats is a delicate business.
Why? Because cats are territorial creatures, it’s completely normal for them to not get along when they first meet.
This means that if you don’t handle the introduction process properly, you could be setting yourself up for failure right from the start.
Not to mention the upset the new arrival might cause the current resident feline(s).
Take it from me – I’ve lived with up to 10 cats at a time (yes, really!) and it would have been impossible to keep them all together (and happy!) without understanding the warning signs when introducing a new feline into the mix.
So here are my 15 crucial warning signs you need to look for that will help you bring in your new family member with minimal drama.
Understanding Cat Body Language
When introducing new cats, it is especially important to pay attention to their body language.
This will give you a visual indication of how comfortable each cat is with the situation – or not.
If you can learn to read and understand cat body language, you can intervene and prevent conflicts before things get ever the chance to escalate.
This is absolutely key to a successful cat introduction.
15 Warning Signs To Watch Out For When Introducing Cats
Cats communicate their emotions and intentions through a variety of visual and vocal cues.
Some of these signals can be quite subtle (e.g., dilated pupils or stiffened posture), while others are more obvious (hissing or a puffed-up tail).
Let’s break it down.
Visual Warning Signs
Visual signals that cats are emotionally aroused (and not in a good way) include:
#1. Dilated Pupils
If a cat’s pupils are dilated, it is often a sign of arousal.
This can range from fear, anxiety, or stress on the negative side to excitement on the positive end of the spectrum.
#2. Staring
Direct eye contact is usually considered as quite hostile in the animal kingdom.
So if one cat is staring down another cat, it could be a sign of aggression and may be seen as a challenge or a threat by the recipient.
#3. Flattened Ears
Cats flatten their ears when they feel threatened or defensive.
This is a clear sign they are feeling uncomfortable or scared.
It also helps stop them from being torn in the event of a cat fight.
#4. Twitching Tail
A twitching tail is often a sign of annoyance or agitation.
It can also be a sign the cat is feeling stressed or anxious.
#5. Puffed-Up Tail
A puffed-up tail (officially known as “piloerection”) is a clear sign that a cat is feeling threatened or defensive.
It is a way for cats to make themselves look bigger and more intimidating in the hope of warding off a potential threat.
#6. Raised Hackles
In the same way, when a cat’s fur is puffed up along their back (aka “raised hackles”), it can be a sign of fear or agitation.
Raised hackles are another way for cats to make themselves look bigger and, consequently, less vulnerable.
#7. Tense Body Posture
If a cat’s muscles are stiffened all over the body, it’s a sign that she is either agitated or fearful.
She may be getting ready to pounce or attack.
#8. Hunched Posture
A hunched posture, where the cat tries to make herself look a little bit smaller, is often a sign that she is feeling uncomfortable or threatened.
By making herself seem less threatening, she may be able to make the other cat go away.
Vocal Warning Signs
If you’ve ever been woken up in the middle of the night by two cats yowling at each other, you’ll already know that cats also use vocalizations to communicate their feelings.
Here are some of the most common vocal signs of negative emotional arousal:
#9. Hissing
When a cat hisses, it’s a clear sign that she’s feeling threatened or defensive.
The hiss is a warning sign that the cat is not comfortable with the situation and would prefer the other cat to remove themselves.
#10: Growling
Growling is a low, rumbling noise and another warning sign that a cat is feeling threatened or defensive.
#11. Yowling/Wailing/Screaming
Yowling, wailing, or screaming are all signs that a cat is feeling extremely threatened or scared.
At this point, things can escalate very quickly into a catfight.
#12. Swatting
Swatting at another cat is a sign that a cat is feeling annoyed or threatened and wants the other cat to go away.
#13. Stalking And Chasing
When a cat is stalking or chasing another cat, it can be a sign of play.
However, depending on the body language, it can also be a sign of aggression and an attempt to intimidate and bully the other cat.
#14. Hiding
If a cat is hiding away, it could be a sign that she is feeling stressed or scared, and doesn’t want to venture out in case the other cat is there.
#15. Blocking And Ambushing
If one cat is blocking another from entering through the cat flap, for example, or ambushing another cat when she’s in the litter tray, these are signs of territorial and hostile behavior – and even bullying.
Why Warning Signs Are Important
Aggression between cats is one of the most commonly reported behavior problems in cats.
Although problematic for cat owners, aggressive behavior is completely normal for cats.
So first of all, try not to get too stressed about it.
In fact, aggressive behavior can be caused by a variety of factors, including territorial disputes, fear, or stress.
It’s always important to keep an eye out for those warning signs of aggression, as the mood can quickly escalate and lead to serious injury in the event of a fight.
The Importance Of Keeping Cats “Under Threshold”
To make the transition smooth when introducing a new cat to your household, your top priority should be establishing a calm and relaxed atmosphere for both the new and existing cats.
Our goal is actually to avoid all 15 of those warning signals long before it ever gets to the point of escalation.
This is known as staying “under threshold.”
In other words, the cats remain calm and relaxed at all times, showing no signs of fear, anxiety, stress, or aggression.
By taking a proactive approach and keeping all the cats’ emotions in check, it means they will be more relaxed overall and less likely to go off the rails emotionally, so to speak.
It’s the best place to start and your best shot at creating a harmonious living environment for all.
How To Keep Cats Under Threshold
The more relaxed our cats are, the smoother the introduction process is going to be.
Any sign of emotional arousal means it’s time to take a break immediately.
By keeping any exposures short and sweet, paired with positive associations (such as high-value treats or play sessions), you can make sure you always end on a positive note while the cats are still calm.
This can mean exposures last just a few seconds, and that’s absolutely fine.
Lots of short positive exposures are far more effective than longer, hostile exposures where the cats are not comfortable with each other.
Don’t Just “Hope For The Best!”
Keeping the cats under threshold also means NOT putting the new cat in with the existing cats as soon as you get her home and letting them just get on with it!
Research shows that when introducing a new cat, about half of cat owners do exactly this – with no gradual introduction process at all (Levine et al., 2005).
If both cats are super mellow and cat-social, this might work but if not, you could have a real problem on your hands.
Personally, I wouldn’t risk it. It’s really not a good idea.
The Importance Of A Proper Introduction
Cats are territorial animals, and introducing a new cat can be a stressful experience for all involved.
A proper introduction can make all the difference in creating a peaceful environment for your feline companions.
It’s also important to recognize that some cats may take longer to adjust to each other than others.
While some cats may become fast friends, others may take weeks or even months to become comfortable around each other.
Be patient and don’t rush the introduction process.
If you do, it may lead to serious conflicts that can take a long time to overcome – if at all.
Managing Cat Introductions
The first step when introducing cats is to manage the introductions very gradually and carefully.
When you know the warning signs, you can take steps to prevent aggressive behavior from developing in the first place.
But I’m getting ahead of myself.
When you first bring your new cat home, the first thing you are actually going to do is keep her entirely separate from the resident cat (or cats) for at least a few days, and maybe longer.
This will depend entirely on the cats, which is another reason why recognizing those warning signs is so important.
Creating A Safe Environment
When you first bring your new cat home, providing a safe space in a separate room is crucial for a successful introduction.
The space can be a bathroom or spare bedroom – anywhere you can kit out with a litter box, food and water bowls, a cardboard box for hiding, a cozy cat bed, a scratching post, and some fun toys.
Your new cat is most likely going to be highly stressed after the car journey, and then being placed in an unfamiliar environment with all those unfamiliar smells and new people.
She’ll have no idea what’s going on or if she’s safe.
In a similar situation, anyone would need some time to calm down, regroup, and get used to her new home, so let’s give kitty that chance before proceeding with the initial meeting.
Introducing her to your existing cats would be a huge mistake at this point, when she is already in a state of high emotional arousal and her stress levels are through the roof.
Later, when you start opening the door, this room can always be your new cat’s safe place to retreat to if she ever feels overwhelmed or threatened.
Slow And Gradual Integration
No doubt your existing cats will know there’s a new cat in the house and may come and sniff under the door – especially if the new cat is quite active or meowing a lot.
Your new cat may even come to sniff back.
Some cats will bat paws under the door – which is great if it’s in play but not if it’s hostile.
If it’s playful, it’s the perfect time to reward the cats for calm behavior with some tasty treats.
If it’s more hostile, draw whichever cat you are with away by throwing a furry toy mouse or pulling a piece of string for her to chase.
Either way, whatever you do, don’t open the door!
Slide treats underneath if you can, but it’s too soon for a face-to-face encounter.
Slow and steady wins the race, and first impressions count for a lot.
Over the next few days, stick with this and watch out for those warning signs.
For the next stage, you can amp things up a bit by feeding the cats some delicious wet food at a safe distance on either side of the door.
Always watch for those warning signs and remove your current cat at the slightest hint of negative emotional arousal.
As time goes on and the cats are staying calm during through-the-door encounters, you can start to open the door a smidge.
Keep exposures short and always look for those warning signs.
End exposures on a positive note before you even get to the need for warning signs, so you can start building up positive associations with the cats being together.
For the next step, when you feel you can open the door completely, consider using a baby gate or screen door to keep the cats separated but visible to each other.
This allows them to get used to each other’s presence without direct contact.
Gradually increase the amount of time they spend together, always monitoring their interactions.
Positive Reinforcement
Use positive reinforcement to create a positive association to encourage calm behavior.
Reward the cats with treats, play, or petting when they interact calmly and positively with each other.
This can help create a positive experience and increase the chances of a successful introduction.
Scent Swapping
In the meantime, you can switch over the cats’ bedding every day or so, so they can start getting used to each other’s scent.
You can do the same with their litter boxes, as long as the new cat has been checked for contagious illnesses and parasites.
You can also swap the cats over so the resident cats can sniff the new cat’s safe space, while she gets to explore the rest of the house.
Considerations For Multiple Cats
If you have multiple cats, the initial introduction of a new pet can be even more challenging.
Try to consider the personalities and preferences of each cat when choosing a new feline companion.
I’ll be honest; I’ve never done that. I just adopt whoever most needs to be rescued!
Regardless, it is essential that each cat has access to multiple resources, including food, water, scratch posts, beds, toys, and litter boxes (one box per cat plus one extra is the rule of thumb).
This way, they can make their own choices as to where they eat, toilet, and sleep.
Not only does this reduce stress and promote confidence, but it also helps prevent competition through blocking and ambushing.
You may also want to try using a Feliway MultiCat Calming Pheromone Diffuser, which can help reduce stress and anxiety in some cats.
What Is Normal Behavior For Cats When Being Introduced?
Studies show that cat-cat aggression is extremely common when a new cat is introduced into a multi-cat household.
It doesn’t mean the cats are aggressive or “behaving badly” and it doesn’t mean you have done anything wrong.
It’s just how it is.
In one study, a staggering 73.3% of owners of multiple cats noted conflict signs during initial introductions.
Factors influencing aggression include unfamiliarity between cats, competition for resources, and territorial behaviors.
The more cats in the home, the more often warning signs were seen.
Staring was the most common warning sign, followed by chasing, stalking, fleeing, tail twitching, hissing, and wailing/screaming (Elzerman et al., 2020).
Another study found that it is usually the resident cats who initiate aggression toward the new arrival.
However, it is also possible for the new cat to be the instigator.
Although aggression may naturally decrease over time, there are instances where conflicts persist for extended periods, lasting months or even years (Ramos, 2019).
This is why it’s so important to do your introductions gradually and provide multiple resources, so the cats get used to sharing their space.
If introductions are not done carefully and warning signals are not heeded, initial fights can be serious, causing harm not only to the cats involved but also to humans if they try to intervene.
In a worst-case scenario, this can result in the new cat being confined – or even relinquished – before she’s even had a chance.
You can prevent this by watching for the warning signs of potential aggression and being proactive about intervening before situations escalate.
Keeping all the cats under threshold like this is the best way to set them up so they can be close friends – or at least tolerant roommates—going forward.
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Resources
- Conflict and affiliative behavior frequency between cats in multi-cat households – L. Elzerman, T. L. DePorter, A. Beck, & F. Collin
- Intercat aggression in households following the introduction of a new cat – E. Levine, P. Perry, J. Scarlett, & K.A. Houpt
NEED HELP FROM A CAT BEHAVIOR SPECIALIST? If you need more help dealing with a training or behavior issue, please find professional help from a certified feline behavior consultant. They will be able to offer you tailored advice for your cat(s) and situation. Good places to start are: - International Association of Animal Behavior Consultants - COAPE Association of Pet Behaviourists and Trainers - American Veterinary Society of Animal Behavior
