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

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....

What a CATastrophe! A Tire-ing Ordeal For a Pony in the UK

As you would expect, our weekly news updates are usually centered around feline topics – we are a cat care website after all...

Ask Dr. Paola – Help! My Cat Has Stopped Eat His Wet Food! (June 1, 2026)

Welcome to our “Ask Dr. Paola” series, where every Monday we bring expert advice straight from Dr. Paola Cuevas (MVZ) to help our...

Chatting About Fake News in the Pet World, AI Again, and New Age Journalism | Chatty Cattys, Episode 23

Navigating the modern digital landscape requires a sharp eye to distinguish fact from fiction. In this episode of Catster’s podcast, Chatty Cattys, Nicole...

More related

Skookum Cat Breed: Info, Pictures, Temperament & More

Known as the Shirley Temple of the cat world, this small and interesting feline is instantly recognizable by its trademark curly coat, which...

Can Cats Share a Litter Box? Vet-Reviewed FAQ & Tips

Although cat litter trays are an unglamorous side of cat parenting, these items are more than just a bathroom for cats, as they...

10 Best Cat Foods for Nursing Mother Cats in Canada 2026: Reviews & Top Picks

Taking care of any cat means being attuned to their health and their happiness. When cats go through different stages of life, a...

12 Best Cat Breeds for Emotional Support (With Info & Pictures)

Cats make wonderful pets, but they don’t have the greatest reputation when it comes to empathy. Instead, they’re generally considered to be self-centered...

Keep reading

Why Do Cats Bring You Gifts of Toys or Dead Animals? Vet-Reviewed Behavior Guide

Everyone loves gifts, but your cat has a very different idea of what qualifies as a present than you do. If you’ve ever been the recipient of a dead bird, mouse, toy, or random object courtesy of your lovable kitty,...

tabby cat carrying a toy in its mouth

Do Oriental Shorthair Cats Shed? Breed Vet -Verified Facts & FAQ

Oriental Shorthair cats are sleek. They have almond-shaped eyes, flaring ears, and a short, fine-textured coat that lies close to the body. Orientals are considered one of the most allergy-friendly feline breeds, but do they shed? The answer is yes,...

close up oriental shorthair cat

8 Best Shampoos for Maine Coon Cats in 2026 – Reviews & Top Picks

It is no wonder the Maine Coon is among the most popular cat breeds in the world. They are known for their sociability and are revered as the gentle giants of the cat world. They come with an uneven, two-layered...

red maine coon in the bathtub shampoo

How Many Bones Do Cats Have? Vet-Approved Feline Anatomy Explanation (With Infographic)

Your average house cat has around 230 bones in their body. That’s quite a few more than the 206 bones in a human’s body! Felines have some interesting adaptations related to their skeletons. For example, cats have a flexible spine...

brown black tabby maine coon cat

3 Homemade Pumpkin Cat Treat Recipes To Enjoy This Fall

Cats are obligate carnivores, meaning they need a meat-based diet. That said, there’s nothing wrong with treating your furry friend to a few little treats now and again, and, if you’re feeling crafty, you can DIY your own cat treats...

Homemade Pumpkin Cat Treat Recipes To Enjoy This Fall

How Long Should You Play With Your Cat? Vet-Verified Facts & Tips

Cats need exercise in order to be at their healthiest. That’s a fact that we’re sure you know if you’re a cat owner, however, you may not always know how long you should be playing with them or even how...

cat playing with owner

Can a Litter of Kittens Have Different Fathers? Vet-Verified Facts & FAQ

Most of the time, littermates resemble each other a great deal, sharing colors and body shapes at the very least. But sometimes surprises crop up, with one or two kittens who look different from their siblings. So, what could be...

tabby mother cat feeding her kittens

Will My Cat Suffocate if They Sleep Under a Blanket? Vet-Approved Facts & FAQ

Once you bring a cat home, it won’t take long for them to find a blanket, a comforter, a scarf, or another type of cover to burrow beneath. While it may look cute, you may also worry about your pet’s...

grey and white cat under the blanket

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.