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.


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

When a Cat Becomes a Water Fountain – Why Cats Vomit After Drinking

Seeing a cat drink water and then promptly bring it back up can be confusing. Sometimes the explanation is fairly simple, particularly if...

Chatting About Sleeping Positions, Loafing & Cats in Tubes | Chatty Cattys, Episode 33

In this episode of Catster’s Chatty Cattys podcast, Dr. Karyn and Nicole dive deep into the fascinating world of feline sleep behaviors. From...

The Bite Stuff: The Truth Behind a Cat’s Sudden Nip

A cat bite that seems to come out of nowhere is one of the more confusing things a cat owner deals with. Everything...

Your Cat’s Purr Proves They’re One of a Kind

There are few sounds more comforting to a cat parent than the familiar rumble of a purring cat. You probably know your own...

More related

Ear Pinna in Cats: Vet-Reviewed Info, Facts & FAQ (With Infographic)

Though a cat’s pointy ears may be just another adorable feature that makes us love them, their ears are highly specialized and fine-tuned...

What Should I Do If My Cat’s Food Is Recalled? 5 Vet-Approved Steps

There’s nothing quite like hearing that your cat’s food has been recalled. Due to major recalls in the past, pet parents know just...

How to Make a Cat Scratching Post from a Log? Step-by-Step Guide

Cats need an outlet for their scratching behavior, and to save your couch and sanity, it’s best to provide them with a scratching...

6 Ways to Save Money on Cat Litter: 2026 Price Guide & FAQ

While cats cost less than dogs to keep happy and healthy, food, toys, and litter can quickly add up and cost more than...

Keep reading

Is Sandalwood Incense Safe for Cats? Vet-Verified Facts and Safety Guide

Sandalwood incense is a common way for people to freshen up their homes and keep their living areas smelling nice. However, it isn’t safe to use around cats. Sandalwood essential oil is known to be toxic to cats, and the...

Catster_Is Sandalwood Incense Safe for Cats

7 Best Cat Litter Subscriptions of 2026 – Reviews & Top Picks 

Next to cat food, kitty litter is one of the most important things that you need when you own a cat. Adding it to your shopping list is all well and good, but the boxes can be unwieldy and heavy,...

orange cat beside litter box

Can Cats Eat Radishes? Vet-Reviewed Facts & FAQ

We all know that cats are carnivores. However, we also know that some cats enjoy human foods, whether animal-derived or plant-based. Many cats do not want to eat veggies unless they’re secretly hidden in their food, but some do like...

Can Cats Eat Radishes

Is Calathea Toxic to Cats? Vet-Reviewed Houseplants Examined 

Animal lovers looking to feather their nests with some greenery should be cautious about which plants they bring into their homes. Our furry friends, especially our cats, love to chew on plant leaves, and they can easily become sick if...

Catster_Is Calathea Toxic to Cats

Why Does My Cat Lick Plastic? Behavior Explained (Vet-Verified)

Cat parents know that felines can do some very odd things at times. Whether suddenly running up the walls (literally) or fitting themselves into the smallest space they can find, cats engage in behaviors that seem to have no reasonable...

cat with plastic bag in the kitchen

How to Stop a Male Cat From Mounting: 7 Vet-Reviewed Reasons & What To Do

Watching your male cat mount various objects, you, or even other animals around your home can be frustrating and confusing. It doesn’t make sense, especially if your cat is neutered. To get the behavior to stop, we have to understand...

cat humping another cat

What’s the Price of Cat Abscess Treatment? 2026 Costs & FAQ (Vet-Reviewed)

If you own a cat that loves to explore the outdoors and has a high chance of encountering wildlife or other pets, they are more likely to get injured. Cats can be territorial, which means the possibility of a fight...

a vet checking a cat's lymph nodes

How to Stop My Cat From Peeing on My Bed: 8 Vet-Verified Tips & Tricks

Picture this scene: you’re home after a long day at work and finally ready to slip into bed and head off to dreamland. You throw the covers back, only to find a large wet spot; your cat has peed on...

Cat sitting near wet or piss spot on the bed

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.