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Why Is My Cat Aggressive All of a Sudden? 9 Possible Reasons

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	Dr. Lauren Demos (DVM) Photo

Reviewed & Fact-Checked By

Dr. Lauren Demos (DVM)


The information is current and up-to-date in accordance with the latest veterinarian research.

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Aggression is not uncommon in cats, and there are plenty of situations that may quickly become stressful for your pet, such as unfamiliar houseguests or poor weather. If your cat displays continuous, uncharacteristic aggression, there is likely something behind the behavior.

To try and resolve your cat’s aggressive behavior, it is essential to know what is causing him to become aggressive. Several causes can spark a cat’s aggression, and you can examine the list below to see if any of them may apply to your cat.


The 9 Reasons Your Cat May Be Suddenly Aggressive

1. Redirected Aggression

Overwhelmed cats may exhibit redirected aggression, which is when they lash out at people or pets who are not the cause of their stress.

An example of this may be when your cat sits in the window and spots a dog outside. Your cat may become anxious and unsettled by the sight of its neighbor. If you or another pet approaches your cat, he may attack in a misguided expression of distress.

If you believe your cat is lashing out due to redirected aggression, it is best to give him space until he calms down. If he is attacking another pet, remove the pets from each other.

agressive tabby cat
Image Credit: Marlon Soares, Unsplash

How to Solve Redirected Aggression

The best way to prevent this type of aggression is to identify the initial cause of your cat’s stress. In our hypothetical scenario, the dog outside caused your cat’s attack. Perhaps you can try to keep your cat from the windows or pull the blinds over the window.

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2. Pain-Induced or Medical-Induced Aggression

Aggression is a common symptom in cats that are either injured or sick. Cats often hide their pain and sickness, making it difficult for pet owners to notice the signs of injury or illness. This also means that your cat may appear aggressive for no reason because he feels unwell.

Some signs that your cat may be injured or ill include hiding, decreased appetite, personality changes, poor grooming, limping, standing strangely or hunched, urinating outside the litter box, and excessive vocalization.

How to Solve Pain-Induced or Medical-Induced Aggression

The best way to solve this problem is to go to the vet. A professional will be able to diagnose your pet’s issues and find the best treatment options available to help your cat feel like his old self in no time.

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3. The Alpha Cat Syndrome

If your cat suddenly shows prolonged displays of aggression, it could be a sign that you are dealing with Alpha Cat Syndrome.

If you have a new pet, your cat could be trying to establish social dominance through aggression. However, even with no further changes to the household, your cat can still try to be an alpha cat. He may bite or make loud sounds to get what he wants as soon as he wants it, such as food or treats.

When your cat lashes out, it is best to avoid confrontation. Walk away from the cat if you are able, and if you aren’t, shut him into a room alone until he calms down.

Scottish fold cat very angry and aggressive
Image Credit: Anatoliy Cherkas, Shutterstock

How to Solve the Alpha Cat Syndrome

The most effective way to handle an alpha cat is through behavioral training. Do not respond to attention-seeking behavior; only offer treats or play when your cat has relaxed. Eventually, your cat will learn that this alpha behavior does not give them the results he wants, and he will change his attitude.

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4. Territorial Aggression

If your cat is feeling territorial, he may become aggressive. If a new pet is in the house, territorial behavior can emerge. Likewise, male cats that are not neutered may also become territorial.

Signs that your cat is territorial include rubbing themselves on objects to leave their scent, clawing furniture, urinating outside the litter box, and being combative.

An excellent way to try and spare your furniture from a cat’s scratching is to buy him a scratching post. If your cat attacks another pet, it is best to separate them and let both pets calm down.

How to Solve Territorial Aggression

Spaying or neutering your pet is the first step to preventing territorial aggression. Giving your cat his own place to escape is another way to try and minimize his territorial instinct, as is providing him with multiple locations for food and water bowls.

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5. Maternal Aggression

If your cat has recently birthed kittens, she may be displaying maternal aggression.

After giving birth, your cat will be hypersensitive to everything around her. Her heightened senses may overwhelm her, causing her to lash out at anyone approaching too closely. In these instances, it is best to keep a careful distance to avoid agitating the mother.

mother cat with kittens
Image Credit: Karen Hogan, Shutterstock

How to Solve Maternal Aggression

In truth, there is no way to solve this aggression, as it is an instinct and will eventually fade on its own. However, it is possible to keep the peace. The best way to do that is to offer your cat a low-stress environment and avoid contact with her and her kittens if possible.

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6. Inter-Cat Aggression

Multiple cats living in one house may lead to inter-cat aggression, especially if one of the cats is a newcomer.

There are two types of inter-cat aggression: overt aggression and covert aggression.

Overt aggression is any obvious, hostile behavior. This includes attacking, hissing, and swiping. Other signs may be that your cat is raising his hackles, thrashing his tail, and keeping his ears flat to his head. His eyes will be dilated.

Covert aggression is much less noticeable but no less serious. Covert aggression can include preventing another cat from using the litter box or getting to the food and water. The aggressor may also combat the newcomer’s attempts to receive affection from you and mark the newcomer’s favorite locations so that he or she is forced to avoid them.

How to Solve Inter-Cat Aggression

It is essential to separate the cats in question to prevent inter-cat aggression. Keep the aggressor in a room with food, water, and litter to himself, and allow the newcomer to roam free. Gradually, you can try to reintroduce the cats under your supervision.

If the aggressor displays poor behavior again, return him to the room and wait some more. The idea is that eventually, he will hopefully learn that there are consequences to his behavior, and he will be less inclined to treat the newcomer with hostility.

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7. Petting-Induced Aggression

Chances are, every cat owner has experienced this type of aggression at least once in their lives. You are petting your cat, you’re both having a lovely time, and then suddenly they are biting you! What gives?

Well, that was petting-induced aggression, and it happens when cats are overstimulated. It is important to know that cats have a threshold for everything, including activities that they normally enjoy. While they may like when you pet them, they only like it up to a point. Then, it becomes aggravating. Biting you is usually their way of telling you to stop.

a woman's hands petting a cat
Image Credit: biubiubiu23333, Pixabay

How to Solve Petting-Induced Aggression

Obviously, we do not want our cats to bite us whenever they want us to stop. So, what can be done?

The best way to avoid this aggression is to learn the warning signs. If your cat is growling, swishing his tail, or flattening his ears to his head, he is probably losing interest. Learning a cat’s body language is integral to caring for your cat, not just for managing his aggression.

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8. Fear Aggression

Fear can often be misjudged as anger in cats. Although your cat is reacting to a situation with aggression, that does not necessarily mean he is angry. Likely, it means that he is scared.

Some other signs that your cat may be afraid are hiding, crouching, flattening his ears, and remaining immobile. He may also have his hair raised and his back arched.

Often, the source of your cat’s fear is something that will pass, such as a thunderstorm. But if the source of your cat’s fear is constantly causing aggression, you have to take steps to remedy it.

How to Solve Fear Aggression

Identifying the source of your cat’s fear is the first step to helping him manage it.  Once you have discovered the source, try to desensitize your cat to it. If you expose your cat to the source from a distance and reward non-aggressive behavior, you can slowly progress towards desensitization.

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9. Predatory Play Behavior

Predatory play behavior is often caused by under-stimulation. If your cat is not receiving enough play outlets, he may have a lot of pent-up energy that bursts out. This energy may come out as seemingly aggressive play, such as stalking, pouncing, and biting. The behavior is more common in kittens, but it can occur in adult cats that are not receiving a proper outlet for their energy.

cat playing with a toy
Image Credit: Darkmoon_Art, Pixabay

How to Solve Predatory Play Behavior

Provide outlets for your cat’s energy and entertainment needs. If you can, purchase plenty of toys so that you can constantly keep your furry friend entertained. Cycle the toys in and out of play to provide more variety.

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How to Best Handle Aggression in Cats

The best way to handle aggression in cats is to start early. The moment aggressive behavior occurs, discourage it immediately. Avoid physical contact or physical punishment. Not only are you likely to become injured in the process, but it is also cruel to your cat and will only reinforce fearful habits.

Try to prevent situations that make your cat aggressive. If your cat does not like when your friend and your friend’s dog come to visit, try to keep friendly reunions out of the house.

If the cat is displaying aggression towards other pets, keep the pets separated before slowly reintroducing them. Offering treats to your pets when they do not display aggressive behavior is a good way to provide them with positive reinforcement during this process.

If you are unable to manage your cat’s aggressive behavior, consult your vet or a behavioral specialist.

woman owner petting and playing with her cat at home
Image Credit: Stokkete, Shutterstock

How to Find Help

If you find yourself unable to manage your cat’s aggressive behavior, consult your vet. It is important to rule out any chance of injury or illnesses.

If there is no medical concern involved, you can talk to a behavioral specialist. A professional will be able to analyze your cat’s behavior and effectively train them to behave properly. Likewise, a professional can teach you how to deal with this kind of behavior.

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The most effective way to handle your cat’s aggression and to soothe them is to recognize the source of the behavior. If you discover what is overwhelming them, you can either remove the stressor or teach your cat how to adapt to it. This will help your cat live a happier life, which is truly what all pet owners want for their furry friends.

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Featured Image Credit: Rudy and Peter Skitterians, Pixabay