Why Do Cats Become Aggressive?

Female cats are usually non-aggressive, but males can behave aggressively towards each other. A healthy cat that is familiar with its surroundings will be easier to calm down.

Cats can become aggressive if they are placed in a new environment, if they just fought with another cat, or because of pain, among other reasons. The approach you take to calm them will depend on the reason they got angry in the first place. Courses of action can include diverting the cat’s attention or ignore it, among other actions.

Signs of an Aggressive Cat

When a cat is angry, it will display certain signs through its body language. As someone who keeps a cat, it is necessary for you to know what these signs are. If you read its body language and determine that it is angry earlier on, it could save you a lot of time and trouble. It could also potentially save you or someone else from getting hurt.


This is one of the first signs a cat will give you, telling you that it is angry. It will start hissing, with a sound similar to the sound a snake makes. The cat will keep its mouth open when it does this. While hissing, it will usually look in the direction of the thing that is making it angry.

If it is looking at you while hissing, it is probably afraid of you. If it is hissing at another pet you might have, it is either scared by it or angry at it. Or maybe it is just asserting dominance over the other animal. When a cat hisses, it opens its mouth so widely that it appears it has partially closed its eyes.

I have a detailed article on reasons a cat might hiss and what you can do over here.

Ears Are Flattened

An aggressive cat will keep its ears flattened. It is common for a cat to flatten its ears while hissing as well. If the ears are pointed outward towards either side, the cat is being aggressive. If the ears are pointed backwards, opposite in direction to the cat’s nose, it means the aggression is due to fear. In such a case, the cat is afraid of someone, and is telling them to back off.

Another sign that the aggression is out of fear, is that the cat will lean backwards, with the front paws placed ahead of the rest of the body.


Cats growl too, just like dogs. They make similar sounds to a dog, usually accompanied by raising the hair on their backs. While, growling, it is usual for a cat to also assume a pouncing stance, which means it will be ready to jump on and attack anything near it. It is better to keep your distance when dealing with a growling cat, because it is warning you that it will attack if you don’t move away from it.

Showing Teeth / Claws

An angry cat is a dangerous cat, because it will not hesitate before hurting someone. But thankfully, it will show these signs to you beforehand, so you know when to stay away from it. It will bare its teeth and claws as one of these signs.

Hair Are Raised

When a cat is angry, the hair on its back will be raised. The cat will also raise its back and tail, making it look larger than it really is. A cat displaying this behaviour is in attack mode, and you should keep a safe distance from it. If it is angry at you, it is better to leave it alone for some time, so that it cools down.

Body Is Stiffened

An aggressive cat will keep its body stiff. This will be apparent in the way it carries its ears sand tail, both of which will be held in stiff positions.

Scratching / Biting

This is the most obvious of the signs. If a cat attempts to bite or scratch you, you need to back off immediately. It also means that it has been giving you hints for too long, and the fact that you haven’t left it alone has only made it even angrier.

Reasons That Make Cats Aggressive

There are many reasons a cat might become aggressive. I’ve listed some of the common reasons below. If you’ve had your cat for a while and know its behaviour and what it dislikes, you will have a better shot at determining the cause of the aggression.

New Environment

A cat that is newly brought into a home can show aggression, particularly if it is older than 6 months. A kitten is weaned and completely stops drinking its mother’s milk by about 2 months of age. 2-3 months old is the best age to rehome a kitten, particularly if you are buying it from a breeder. Because at this age, the kitten is ready to explore the world and see how things work. They are extremely curious and energetic at this age.

If the kitten starts growing older in one home, with the people in that home, it will get attached to that home and those people. Then, if it is rehomed after it has formed a bond, if is likely to either be afraid of the new people, or show aggression. If it shows aggression, it is because it doesn’t know who the people in the new home are and doesn’t trust them yet. It will take some time and work to prove to the cat that the new owners are friendly and won’t hurt it.

Fighting With Another Cat

If a cat has just fought with another cat (or any other animal for that matter), it will likely stay angry at everything for a while. If a problem needs to be addressed, you can address it and then leave the cat to chill out for some time. If the cat has already isolated itself, then let it be alone for a while.

If you have two cats that fight often, one of them is usually the one that provokes the other. You will need to observe why it starts attacking the other one. Do you have more than 2 cats? Does the attacking cat always single out the same cat to attack? Is there a pattern to it? You will need to observe and try to think from the cat’s perspective, to find out the underlying reason for the aggression.


One day you are sitting with your cat on your lap and petting it. Then it suddenly screams, scratches or bites you and then runs away. If this happens, you’ve probably touched your cat somewhere it hurts. Instead of running, the cat could even curl up right there in your lap and start growling.

You will need to comfort it slowly by petting it on the head, on the back or under the chin. Cats generally dislike being touched on their bellies and tails, unless they are in the mood for it. So touching both these areas on a stressed cat should be avoided. The cat could potentially attack if touched there in a painful situation

It may take a while to figure out the reason for its aggression. Reasons for pain include indigestion, injury from fighting with another animal or accidental injury while being too curious and going somewhere it shouldn’t be going.

Territorial Aggression

Cats can become very attached to an area of the house, or a toy / piece of furniture. They will spend lots of time in that area, or near the object that they like. When they become fond of an area or object, it will automatically become theirs. The cats will announce that it is their property by spraying on it. Most males and some females spray a little bit of urine on it to announce to other cats that something is theirs.

If someone else goes in to that area or takes that toy, they can become aggressive, because they want it for themselves. If the object they like is a cat toy, then you can leave it for them. But if it is something that you need, like a cushion or something, you can hide it when the cat isn’t around. Or, you could provide a substitute for the cat to get attached to and replace it with a cat toy for a few days.

If the cat is attached to a place that is needed for other purposes, you could slightly rearrange the furniture there, putting more obstacles for the cat. Doing this will deter the cat from being aggressive.

Afraid of a Person

We have seen that a cat can be afraid of people when it moves to a new environment. However, even once it has settled down and become more familiar with the surroundings, a cat can remain afraid of a particular person. Or maybe it doesn’t trust that person.  So, if it is showing signs of aggression towards a specific person, that person will need to win the cat’s trust. To deal with such a cat, you can read the first 2 points below, under how to calm an aggressive cat down.

Protecting Kittens

Mother cats can show aggression when taking care of their new-born kittens. This usually happens when the mother is not comfortable with you, as pet cats that have formed a bond with their owners won’t mind having their kittens touched. However, the kittens are very susceptible to infections and should be left alone for the most part. Proper hygiene needs to be maintained to avoid infections in the little babies, as even a small infection can be fatal for them.

Some Other Reason

There could be any reason for a cat to become aggressive. You, as the cat’s owner, are the best person to observe and determine why and when it gets angry. For example, if it attacks anyone coming close to it during feeding time, it’s not a big issue. Just leave it alone when it is eating. Unless it is a very young kitten, it will probably not hurt you anyway. Something as simple as a sudden loud sound could also scare and confuse your cat, making it show signs of aggression.

Looking for patterns will help you figure out the cause. Like, does it get angry in similar situations? Did it always get angry in such situations, or did it recently start getting angry / irritated? If it started recently, what changed? Did you get another cat? Or maybe it was attached to a certain member of the family, who isn’t around since a few days?

Kittens that were not socialised properly during their first few months may also show aggression, as will older cats that have spent most of their lives at a shelter. They won’t be used to receiving personal attention and care from a human, so will probably be confused and scared when it happens for the first time. Remember, observe and think from the cat’s perspective. It should get you to the underlying cause of the aggression.

How to Calm an Aggressive Cat Down

Before we try to calm down an aggressive cat, it is absolutely essential to protect ourselves first. A person should be able to tell when the situation is serious, and when to seek professional help. An aggressive cat can seriously hurt you. I have an article on how to groom a cat, where I’ve also mentioned the proper technique to cut the nails of your cat. Cutting a cat’s nails regularly in the proper way will make it easier to handle if it behaves aggressively.

Be Calm

The first step while dealing with an aggressive cat is to remain calm. Even if you are feeling anxious, do not let this be apparent in your actions, otherwise the cat will be harder to calm down. Being calm tells the cat that you are not afraid of it. If the cat senses that you are intimidated by it, it will behave more and more aggressively. You should also avoid any sudden movements, so the cat doesn’t get startled further. When the cat realises that you are not afraid of it and won’t hurt it either, it will calm down a lot quicker.

Intentionally Ignore the Cat

This step works wonders, but requires some time and patience. Also, it won’t work if the cat comes toward you to attack you. If it maintains distance, you can go ahead.

If the cat is being aggressive toward you, you can spend more time with it. Go in the same room as the cat, and close all doors and windows, so it stays within the room. Then, go about doing something, by yourself. You could be on your phone, read a book, or something else.

Keep some distance between the cat and you. The activity you choose to do shouldn’t make loud noises, and you should be where the cat can see you easily. Chances are, it will be staring at you for most of the time.

When the cat stops being aggressive and minds its own business, you can move a couple of feet closer to the cat. If it stays calm, you can continue your activity. Don’t look at it too much. Just occasionally glancing at it to observe its behaviour should be enough. And whatever you do, DO NOT look directly into its eyes. The cat will see this as threatening or a challenge, making it more agitated towards you.

You can slowly move closer and closer to it, as long as it allows you to. It may allow you to come close to it on the same day, or it could take a few days. Once you it allows you to sit right next to it, you can attempt to pet it on the forehead. Use gentle and slow movements. If it closes its eyes while you are petting it, it means the cat has accepted you. If it starts purring, even better! Congratulations! You’ve just won a cat’s trust.

Know When to Give it Space

If the reason for the aggression is a fight with another pet or a human irritated it, the aggression should go away soon. You will just need to give it space and not interfere. Even an attempt to calm it down could be seen as interference.

Divert its Attention

If the cat is fixated on something, you will need to divert its attention. The cat will constantly stare at the thing that is making it angry. You could put a visual barrier between the cat and that object. Place a cloth on top of the thing that has your cat’s attention, or put something in between them both so the cat can’t see it anymore. It should be enough to immediately put a stop on the aggressive behaviour.

Isolate it if Needed

Sometimes you just need to keep a cat alone in a room with minimal contact for a few days. I once had an aggressive male. I kept him isolated, away from all the other cats. A few days later, when I would go near him to feed him, he would lie down on his back and let me pet him. He never behaved aggressively after that, and became quite loving.

This step will work even better if it can see you or your other pets going about their daily routines from that room.

Do NOT Punish It

This is a very important point. Whatever you do, do not punish the cat. Even if it poops on your bed or tears up your couch. If you hit your cat or even yell at it, chances are it will become afraid of you. And if a cat didn’t feel threatened by you before but does now, it takes a LOT of time and conscious effort to build that trust back. There are better, friendlier ways to discipline a cat.

Get Professional Help (Vet or Cat Behaviourist)

If the cat doesn’t appear to be too dangerous, you could try the above steps. If it is dangerous to attempt these steps, or if you’re not sure how your cat will react, you should call your vet or a cat behaviourist. Consult the vet or behaviourist before isolating it in a room.

Syed Baseeruddin Hyder

I’ve been keeping fish and invertebrates in aquariums for over 5 years. Over the years, I’ve kept more than 15 different species of fish and invertebrates. Through ParadiseInATank.com, I hope to guide new and experienced fish keepers alike with as detailed information as I can get.

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