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Why Do Cats Hiss and Growl at Each Other?

Many cat owners will see the uglier side of their pet when it crosses paths with another cat. Often this will occur when a new cat is adopted into the family.

Even if an introduction goes very well and the proper steps are followed, most likely there will be hissing and growling. Hisses, growls, gentle swats, pinned ears, and other clearly upset behavior is a cat communicating distress or aggression. 

While canines have evolved to be social creatures, cats have evolved to be, mostly, solitary creatures. Making friends can be difficult, and keeping them can be a challenge as well.

Although cats have a natural inclination toward solitude, early socialization with other cats, humans, dogs, and others can make a huge impact on their future ability to be social. If the cat is not used to other animals, a new cat is a break from the daily routine and environment.

This is a disruption and, potentially, a threat. 

But why do cats hiss and growl at each other? Mainly, it is a warning. If a cat feels threatened, it will begin to hiss and growl, accompanied by puffed fur, arched back, and sometimes crazy tail posture.

Another cat is an unknown, and unknowns are scary. Although, hissing and growling are not always so harsh and can be translated as a cat simply asking for more space. 

Reasons why cats hiss and growl

#1 Fearful and/or angry with other cat’s presence

If not properly introduced, cats have a tendency to not get along. This does not mean they will ignore each other as polite humans might, but most likely will end up in a hissing match.

It is possible for the cats to begin fighting, as well, if the warning of hisses and growls is not listened to. A cat might fear a newcomer and will hiss and growl at the new cat as a warning to get out of their space. 

Social behavior sets in early, especially for felines. A cat who has had little to no socialization with other cats will have a tough time adjusting to a new housemate.

Imagine an elderly human who has lived alone their whole life, only to be told now they will share all of their home with a stranger. Or an only child who suddenly has an adopted sibling.

This would be difficult for anyone. This is why it is extremely important to socialize cats as young as possible. After the kitten stage, their manners and habits toward others are usually set for the rest of a cat’s life. 

#2 Familiar cats become unfamiliar

After a trip to the vet, it is common for the returning cat to be snubbed by its housemates. Sometimes, they will even be attacked.

This causes emotional distress for all the cats involved. It seems the cats do not recognize each other, which might be true in many ways. Though an element of familiarity might remain, the cat that went to the vet or groomer now has an altered scent. 

Cats communicate through sight, sound, and scent. If any of these change, it cues the cat that something is different.

Scent is an identity tag. The once-familiar cat smells too different to be trusted, as this might be an entirely new feline, an interloper.

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The cat or cats who stayed home are distrustful of the cat who left the house. They don’t know where they went or why, and now they smell like strangers and medicine upon return. 

Even siblings who have lived together their whole lives and are separated for a short duration will become unfamiliar and lash out at each other. 

A cat’s scent can change as well if it is sick, as the body chemistry changes. Keeping a sick cat separated until and after a vet’s visit will provide space for the sick cat to recover in peace and safety, as well as limit defamiliarization. 

A good tip for reducing this separation, if it is because of a visit to the vet, is to schedule regular appointments together. If both or all of the cats go to the vet at the same time and return home together, they will smell similarly and the likelihood of an attack is greatly lessened.

There will be no individual target and everyone will just be happy to be home. 

Read our article “Why is My Cat Scared of Other Cats?”

#3 Redirected aggression

Aggression includes hissing, growling, swatting, chasing, and even going in for bites. If cats are startled by something, such as a loud sound, they will assume a startled posture which resembles the warning and fighting posture.

It is defensive, and another cat nearby who might have also been startled will see the defensive feline. It is possible as well the cats both think the other caused the thing that startled them.

A startled cat will often use a “surrogate” target in place of the actual perceived threat because they can’t get to the actual target, or doesn’t know what it is. 

The reactions of the cats to what startled them results in both of them becoming defensive. So, they redirect their resulting aggression on each other. They will hiss and growl as if they were about to fight.

If a human were to intervene when the cats are defensive and ready for a fight, they might become the new target of the redirected aggression. 

Redirected aggression is similar to when familiar cats become unfamiliar, but the difference is in the source of conflict. While taking one cat to the vet might cause unfamiliarity between housemates, this is a predictable behavior and easy to avoid if you follow a proper reintroduction procedure.

Redirected aggression is much more unpredictable. It could happen any time cats become startled or uneasy around each other. But both problems can be solved. 

How to calm a cat who is hissing and growling at another cat


If worst comes to worst, you can always stop a cat from attacking another animal by throwing a towel over it. Make sure it is a thick towel or blanket so the cat is trapped and able to be carried to another room.

If two cats are increasing their aggression, and it is clear a fight is about to ensue, throw the towel over the more aggressive one. Make sure you do this and pick them up quickly, or else the cat might escape.

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Though a thick towel should make them pause for a moment. 

Keep the cats separated, in different rooms, for a couple of days if necessary. Then, follow the next tips on introducing new cats.

Though cats might know each other, you will often need to reintroduce the cats after an aggressive event to fix the damage. 

How to provide the best possible introduction of new cats

Introductions can be tricky. Take steps to ensure a safe introduction or reintroduction. Here are some steps and tricks to use:

  • Before bringing an unfamiliar cat into the home, pet the cats already established in the home with a towel, rubbing their head as much as possible along scent glands. Then, pet the unfamiliar cat with the scented towel. This will build familiarity with the new cat. Distraction scents, such as catnip and tuna are good as well. 
  • Set up the unfamiliar cat in a room on its own, so the cats may sniff each other from a safe distance and behind a closed door. After a day or two, allow the cats to exchange places, so that scent is thoroughly familiarized before any actual contact. 
  • Allow some form of moderated contact, such as a securely cracked door. This way minimal contact is allowed, but they could not get to each other enough to fight. Feed the cats a special treat on either side of the door, so they eat together. Make or buy a toy that fits and stays under the door for them to play together. 
  • When both cats are relaxed around each other’s presence, the door may be opened and the cats fully introduced. If any aggression such as hissing or growling occurs, separate them and try again later. Let them become acquainted for a short time, even if it goes well. Increase the time of acquaintance as you go until they are completely comfortable around each other.

How to tell the difference between real and play fighting

Sometimes play between two cats can become rough. However, there are telltale signs that the two cats are play fighting and not really fighting.

Play fighting is mock aggression, which is common in kittens and siblings who have grown up together. If they are playing, they will take turns being the aggressor and sometimes appear lazy about their attacks.

Their body posture will not be as severe as in real fighting, with their ears up and their body forward. They will stalk, chase, and pounce on each other for fun.

They will even throw each other to the ground and bite, but never intend to cause damage during mock fights. Hissing and growling are also huge indicators, as cats who are play fighting will typically not hiss or be vocal in any way. Vocalization of aggression is the biggest sign of a real fight. 

Final Thoughts

Though cats hissing and growling at each other can be frightening, it is very normal and often subsides before any physical attacks. Proper introductions, reintroductions, planning ahead, and reading the situation are essential tools for ensuring the least conflict possible.

If your cats are prone to hissing matches, keep a towel or blanket at the ready just in case.