Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Dealing With an Aggressive Cat? 7 Vet-Verified Reasons Why Cats Become Aggressive

Share

owner petting a hissing angry tabby cat

Even the most experienced cat caretakers can find themselves charged up on adrenalin when having to face a cat in the midst of a fit of aggression. But encountering a hissing, growling, screaming, and possibly even scratching and biting cat can strike terror into the hearts of people who don’t know how to handle an aggressive cat.

But cats don’t just suddenly go crazy: There are almost always warning signs and there’s almost always a good reason for cat aggression. Here are seven reasons why cats become aggressive and how to handle an aggressive cat.

divider 3 paws

The 7 Main Reasons Cats Become Aggressive

1. Cats Become Aggressive Because They’re in Pain

Cats who are in pain will respond with hisses and swats when sensitive areas are touched. My cat, Siouxsie, does this if I accidentally put pressure on her sore hips. A hard yank on the tail, for example, can be quite painful. Ignore the warning signs and a scratch and possibly even a bite may follow. This is especially true if the pain is a result of physical abuse such as being kicked or hit.


2. Fear Can Cause Cat Aggressive Behaviors

A terrified cat will respond with body language that’s obvious to an experienced cat caretaker: She will turn sideways and puff up her tail and fur in order to look larger. Her ears will flatten backward, she will hiss and her pupils will dilate. Attempting to approach a cat in this state is risking an aggressive reaction, not because the cat dislikes you but because she’s in the middle of a panic reaction.

An angry cat growling, hissing or hiding.
An aggressive cat might be responding to pain. Photography ©points | Thinkstock.

3. Hormones May Contribute to Aggressive Behavior

Cats who haven’t been spayed or neutered can display hormone-driven behaviors, including certain behaviors perceived as aggressive. Intact males, in particular, may fight with other males when a female in heat is nearby, as they naturally compete for mating opportunities. If you witness two cats fighting, avoid stepping in physically—there’s a high risk of being scratched or bitten. Instead, use loud noises or another safe distraction to break up the conflict from a distance.


4. Cats Can Get Aggressive Due to Frustration

“Redirected aggression” is the term used when cats behave aggressively towards other pets or humans because they can’t reach the object of their predatory passion. For example, an indoor cat who sees another cat walking by or marking his territory in “his” turf may get into a highly reactive state. At that point, anyone unfortunate enough to be nearby, whether that’s another cat, a dog or a person, may end up on the receiving end of the cat’s aggression.

A kitten hissing with his ears flattened back.
Image Credit: Ornitolog82, Thinkstock

5. Cat Aggression Happens Due to Stress

If a cat lives in a highly stressful environment — for example, a home in which people are fighting or a home with too many cats — it’s quite possible for that cat to be quick to respond aggressively. Like children who live in homes with a lot of verbal and physical violence, or a lot of unspoken anger, cats often act out the dynamics of their human families.


6. An Aggressive Cat Might Be Responding to Trauma

Don’t laugh: Cats can suffer from post-traumatic stress. Their brains are wired similarly to ours, and the effects of chronic anxiety from past human violence or struggling to survive on the streets can lead cats to become aggressive. To resolve this issue, a short course of anti-anxiety medication (prescribed by a vet, of course; don’t give your cat your antidepressants, please), homeopathic remedies or flower essences can help make a cat less reactive to triggers. Ask a veterinarian for more options on how to successfully and naturally calm your cat.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money


7. Hyperthyroidism Can Contribute to Aggressive Behaviours

Although it’s not the most common cause of aggression, medical conditions like hyperthyroidism can lead to noticeable changes in a cat’s behavior. When thyroid hormone levels are elevated, some cats may become unusually irritable, restless, or reactive. In these cases, treating the underlying thyroid disorder is essential, as behavior often improves once hormone levels are properly controlled.

Related: Do You Have an Aggressive Cat — or Just a Brat?!

divider 3 paws

The bottom line on handling an aggressive cat

No matter what the cause of the aggression, there are almost always warning signs. If you understand feline body language, you will be able to see that your furry friend is getting wound up before the situation escalates to a crisis point. If you have a highly reactive cat and you want to help him or her, be aware that it will take time and patience — but take it from a person who has rehabilitated traumatized cats: The reward is so worth the effort!

Related Reads:


Featured Image Credit: Anna Kraynova, Shutterstock

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.




How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.


Catster's Digital Magazine is Back!

Vet-approved health & behavior advice

Real cat stories & community features

Chatting About the Rainbow Bridge, Euthanasia, and Laughter During Grief | Chatty Cattys, Episode 24

If you’ve ever felt the loss of a beloved cat, or are dreading the day when your pet crosses the rainbow bridge, you’ll...

The Simple Reasons Cats Refuse to Let Anyone Use the Bathroom Alone

Cats have an extraordinary talent for making themselves present in the most inconvenient places, and the bathroom ranks near the top of the...

A Paw-sitive Milestone: Canada Officially Becomes a Declaw-Free Nation

Canada has officially become a declaw-free nation. On May 25, 2026, a new regulation was filed in Ontario under the Provincial Animal Welfare...

The Surprisingly Simple Ways to Help a Cat With Hairballs

Cats spend an astonishing amount of time grooming. It is part hygiene routine, part comfort ritual, and part instinct that traces back generations....

More related

Do Calming Collars Work for Cats? Benefits, Side Effects & FAQ

Disclaimer: Opinions expressed by the author do not necessarily reflect those of the veterinary reviewer. Does your cat get stressed easily? Maybe your...

Pandora’s Syndrome in Cats: Causes, Signs & Treatment (Vet Answer)

Have you ever been stressed for a long time, and as a result of this had a bad skin break out or picked...

How Long Does CBD Stay in a Cat’s System & Is It Safe? Our Vet Explains

Cannabidiol, also known as CBD, has been growing more and more popular in recent years. It has many benefits for humans, such as...

Are Lightning Bugs Poisonous to Cats? Vet-Reviewed Facts & FAQ

Lightning bugs, or fireflies (family Lampyridae), can be fun to watch and relatively easy to find on a summer evening. Your cat also...

Keep reading

6 Potential Side Effects of CBD Oils for Cats: Vet-Reviewed Science & Facts

Many cat owners are turning to holistic approaches and natural supplements like CBD oils to treat their felines. As these alternative treatments keep undergoing research, it isn’t much of a surprise that more pet owners are getting invested in the...

Man giving CBD oil to a cat

Why Does My Cat Stare at Me Without Blinking? 5 Vet-Reviewed Reasons

For as much as we might try to meow back and forth with our cats in an attempt to communicate, our efforts are inevitably futile. However, there are ways for your cat to let you know how they are feeling...

glowing eyes

How Long Does It Take a Cat to Adjust to a New Home? Vet-Reviewed Facts & FAQ

There will be an adjustment period whenever you bring home a new cat. While all animals need an adjustment period to some extent, cats typically have a more dramatic adjustment phase. While dogs may be more prone to accidents and...

Savannah kitten

Will Your Cat Miss You If You Give Them Away? Cat Emotions Explained

Cats are loyal, loving animals that can form strong bonds with their owners. But what happens when you give your cat away? Is it possible for them to miss you, even if you’re no longer in their lives? Yes, cats...

sad lonely cat lying on bed

Why Do Cats Cry at Night? 8 Vet-Reviewed Reasons

Our cats are creatures of the night, so it’s no wonder you hear them howling their song into the echoing chambers of the house when all are sleeping. With as much as you’re getting used to the sound of a...

Ginger tabby young cat sitting on a wooden floor looks up, asks for food, meows

Why Do Cats Rub Their Face on Things? 6 Vet-Verified Reasons

Cats do all sorts of strange and wonderful things, like racing around your house at 2 a.m. or hiding dead mice under your shoes. But have you noticed that your kitty seems to like to rub their face on everything...

american shorthair cat rubbing face on the wood

Is Declawing Cats Illegal in Australia? Vet-Verified Facts, Reasons & Alternatives

Declawing cats is heavily regulated in Australia, meaning that it is banned as a standard procedure and only permitted if it’s essential for the cat’s health.¹ Routine declawing is also illegal in several other countries, though it is still legal...

cat claws when kneading

Will Insulation Hurt My Cat If They Touch It? Vet-Reviewed Prevention Tips & Safety Info

Most (but not all) wall or hardware insulation isn’t going to harm your feline if they only touch it. However, it isn’t digestible, so if your feline eats it, it can cause chemical toxicities and/or gastrointestinal blockage. Such incidents are...

Foam construction insulation

Love Cats? So Do We! Join the Catster Community

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.




Sign up for the Catster Email Newsletter

Stay informed with expert pet care insights delivered straight to your inbox! Discover professional guidance on animal behavior, feeding tips, trusted product picks, and much more.