Cat Acting Strangely? Here’s What It Could Mean

Your kitty's recent behavior changes have got you worried, haven't they? The truth is, when a cat is acting strangely it can be due to three major factors: natural life cycle changes, stress, or an indication of an injury or disease onset. In this article, we will examine these typical changes in cat behavior and interpret what they could mean.

It's true, both gradual and sudden alterations in your cat's demeanor deserve your attention. As loving cat owners, our role is to monitor these changes and act when needed. But what actions are appropriate?

We'll explain what you should do if your cat starts to behave unusually. We will also explore normal behavioral adjustments in cats as they mature, and point out certain changes that are not a normal part of a cat's life and could signal a health or behavior problem.

This guide will provide insights into expected behavioral changes that occur throughout your cat's life cycle, such as maturing from a kitten into an adult cat or growing old. We will also highlight unexpected behavioral changes that might hint at a problem, such as increased aggression, changes in eating or drinking habits, or unusual fear and hiding behavior.

Lastly, we will tackle sudden, out-of-the-blue behavioral shifts that may not be related to the cat's life cycle at all, such as "My cat suddenly stopped eating" or "Why is my cat suddenly so affectionate?"

Stay with us as we help you understand your cat better and ensure its well-being.

Is your cat acting strangely? Is Kitty suddenly aggressive? Is she hiding from you, or perhaps she's stopped eating? Here's what changes in a cat's behavior could mean and what you should be doing

Understanding Kitty's Unusual Actions: A Brief Overview

Understanding your pet's behavior changes is critical and it usually boils down to three primary factors:

  1. A natural change in the life cycle (growing old, going into heat, etc.)
  2. The result of an injury or the onset of disease.
  3. A symptom of stress—sudden or prolonged.

Whether gradual or sudden, a change in your cat's behavior should indeed be a cause for concern. Changes in feline behavior can mean many things. As owners, we have to watch out for such changes and take action when necessary.

What to do if your cat is behaving strangely

The answer depends on the type of change. Keep reading to find out the change your cat is going through—and what to do about it.

Some changes in behavior are normal.

Cats adjust their behavior as they grow up. Kittens act differently from adults, and senior cats often display a different temperament than that of younger cats.

Then again, some changes in behavior are not a normal part of a cat's life. These can indicate the onset of an actual health or behavior problem.

Let's go over the normal - and the not-so-normal - changes in feline behavior and see where your cat fits in and what you need to do.

Expected behavioral changes relating to the cat's life cycle

In a nutshell, these are the changes a cat experiences during the feline life cycle:

  1. Maturing from a kitten into an adult cat
  2. Going into heat (for non-spayed females)
  3. Sexual maturity (for non-neutered males)
  4. Growing old

Unexpected behavioral changes

These changes are often more sudden and are likely to be a sign that the cat has a problem. They include situations where your cat begins to -

  1. Display needy behavior
  2. Avoid eating or drinking
  3. Seem scared and hide
  4. Bite and generally show signs of aggression
  5. Avoid the litter box
  6. Act strangely after being outside

We'll cover these and more in this guide, starting with normal behavior changes during the lifetime of a well-adjusted and generally healthy cat and moving on to the more mysterious sudden, and unexpected changes in behavior.

What are Normal Behavior Changes in Kittens?

Generally speaking, kittens are more energetic than adult cats. They tend to be more curious, explore their surroundings, and play with their siblings or other pets in the household. This is how kittens learn about the world and what being a feline is all about.

That's why kittens need close supervision to make sure they stay out of trouble. They can also be quite tiring, as they seem to relentlessly jump, bite, chew on things, climb, and generally interact with everything and everyone between long sessions of deep sleep.

This eventually changes.

As they grow older and mature, kittens calm down and lose the hyperactive streak. This is a gradual process that usually begins when the kitten is 4-6 months old and with some cats can take up to 2-3 years.

Behavioral changes in non-neutered male kittens as they mature

Male kittens usually reach sexual maturity between 5 to 8 months of age. When those male hormones kick in, the kitten's behavior is likely to change.

The kitten will generally become more territorial and may display the following:

  • Increased aggression levels toward other cats and people
  • A tendency to roam (indoor-only intact males may try to get out)
  • Urine spraying around the home

Not all males become aggressive or spray urine, but most do. The only way to stop these unwanted behaviors is by neutering the male to lower the levels of testosterone. Once these behaviors turn into habits, even neutering doesn't always help.

The solution?

An ounce of prevention is definitely a pound of cure in this case. Has your male kitten been neutered before the age of five months to make sure he doesn't develop these behavior problems?

Behavioral Changes in Female Kittens as They Mature

Female cats usually reach sexual maturity between the ages of five and seven months. Once that happens, the female will routinely go through heat cycles during most of the year (with the possible exception of winter months).

During the heat cycle, the female will display significant behavioral changes—all of them due to the fluctuating hormones in her blood. The heat cycle will last 1-2 weeks, during which the female may display the following behaviors:

  • Excessive affection
  • Head rubbing against objects and people
  • Loud meowing
  • Crouching on the ground and extending the neck upwards
  • Possible urine marking or just urinating outside the litter box

The solution?

Responsible cat owners spay and neuter their pet cats before they are five months old. This is usually enough to prevent female kittens from going into heat.

Please save your cat from the stress of the heat cycle and prevent unwanted pregnancies by spaying Kitty in time.

How Does a Cat's Behavior Change After Spaying or Neutering?

Generally, cats become less aggressive, more playful, and inclined to seek an owner's attention following a spaying or neutering procedure.

If the cat had already reached sexual maturity then neutering/spaying will stop the unwanted behaviors associated with that. Roaming, fighting with other cats and spraying will decrease significantly in neutered male cats. Female cats will stop going into heat.

What are Normal Behavior Changes in Aging Cats?

Just like humans, cats slow down with age. Many will experience some decrease in sensory abilities. They don't hear and see like they used to and might display their version of "senior moments".

Fortunately, most cats do not become senile and can enjoy their golden years. In terms of behavior, they may "slow down" a little but should remain active and in good health.

And then there are those who have a more difficult time coping with old age.

Some aging cats may experience a decline in mental functioning known as FCD or Feline Cognitive Dysfunction.

Cats suffering from FCD present deficiencies in hearing, vision, general awareness of their environment, memory, and ability to learn. FCD can disturb normal sleeping patterns, reduce activity, and disorient cats at times. In some cases, older cats with FCD forget where their litter box is located and urinate or defecate outside the litter box. Unusual aggressive behavior can also emerge in typically mellow cats as their confusion and memory loss increase.

Signs a cat is having episodes of disorientation include:

  • Getting lost in a familiar environment
  • Fixating/staring at an object
  • Staring into space for extended periods
  • Wandering aimlessly in their home
  • Excessive vocalization, especially at night

Cats with feline cognitive dysfunction may also appear less interested in interacting with owners, greeting people they know, or socializing with other pets. Alternatively, some cats become clingy and over-dependent, desiring more contact with owners. Additionally, they may eat less, groom themselves less frequently and vocalize loudly for no apparent reason.

When should you talk to your vet?

Any abnormal behavior in an aging cat should be evaluated by a veterinarian to determine if the cause is FCD or illness. Degenerative and/or painful disorders such as arthritis, urinary tract disease, thyroid dysfunction, or diabetes can increase irritability, sensitivity to being touched, and instinctual aggression in cats regardless of their age.

Don't forget to talk to your vet about routine checkups. Their frequency should increase with age. Just how often would depend on the cat's age, overall condition, and the amount of stress he or she experiences by going to the vet.

Behavioral changes in cats that are not related to life stages

And now it's time to address the other kind of behavioral changes in cats. The kind that isn't related to the cat's "normal" life cycle.

We like to call it: "My cat suddenly..."

These could be changes with very sudden onset indeed:
"My sweet-natured Fluffy suddenly attacked me!"

Or the onset could be a tad more gradual, taking hours, days, or even weeks:
"Over the past week, I've noticed my cat has become more clingy than before."

So, what's going on?

Let's explore various scenarios to learn more.

"Why is my cat suddenly so affectionate?"

If your cat hasn't been spayed yet then chances are she's going into heat. In many females, excessive affection is often the first sign. Now would be a good time to call your vet and set up a date to get her spayed as soon as possible.

If Kitty is already spayed—or is a male—you need to look for other causes.

If by affectionate, you're referring to purring more than usual, this could actually indicate pain. See our article about signs of pain in cats to check if other signs are present and talk to your vet.

Just to clarify—it's perfectly natural for a cat to be affectionate. It's when an adult cat suddenly becomes significantly more affectionate and even clingy that you need to figure out what's going on.

Many cats become clingy when their owner returns after being away from home for a long while. A list of potential stressors in cats and ideas on how to help alleviate that stress.


"Why has my cat stopped eating or drinking?"

The top reason cats refuse to eat or drink is that they're not feeling too well.

This could be something minor that soon goes away by itself. For example, a lack of appetite can follow a minor viral infection, any sedation or anesthesia procedure, or sometimes even vaccinations.

Or it could be something more substantial.

Teeth and/or gum infections often make it too painful for a cat to eat or even drink water. So would anything that becomes lodged anywhere in the cat's mouth or nose. Of course, infections and other diseases can also cause a lack of appetite.

Stress caused by environmental and household changes may also interfere with a cat's appetite. If you bring home a shy cat, he or she may refuse to leave the security of that dark place behind the couch, even to drink or eat. That's why you should always introduce a cat to a new environment gradually, creating a safe room where the cat will have undisturbed access to food, water, and the litterbox.

Here's the thing:

While it's not unusual for a cat to refuse to eat or drink for a day, cats that haven't eaten for 24 hours or longer should be seen by a veterinarian. Rapid weight loss can cause a serious disease called hepatic lipidosis, to the point of liver failure.

So, what can you do about it?

If your cat has stopped eating and hasn't had any food in 24 hours, call your veterinarian. Kitty will need to be assessed and treated as soon as possible.

Read more about our guide about how to get a cat to eat again, filled with advice given by experienced cat owners.

"Why Does My Cat Suddenly Act Frightened and Hide?"

Well, your cat is probably afraid. The question is—of what?

First, let's talk about medical issues.

A cat may actually try to hide away from pain. In fact, many owners of outdoor cats have noticed how their cats wander off and hide under a bush when the time comes for them to die. Watch for other signs that your cat may be in pain and talk to your veterinarian if you suspect Kitty may be ill.

Once you rule out health issues, it's time to look for whatever it was that scared your cat. Sometimes the answer is easy. A new pet, a visitor, fireworks outside, or even seeing a strange feral cat through the window can send a timid cat into hiding.

For some cats, going to the vet is a nerve-wracking experience and requires a period of time to de-stress once they get home. Hiding may be a cat's way of calming themselves down before returning to normal behavior.

What to do if your cat is suddenly hiding?

The key here is to figure out what's bothering your cat and address the cause of the fear. Never force a cat out of his or her hiding place. Find out what's bothering her and fix the issue. Follow the steps in this guide:
How To Get A Cat To Come Out Of Hiding?

"Why has my cat suddenly started biting?"

Cats bite or nip owners for a variety of reasons. Some cats are more aggressive than others, or they may be too sensitive to petting. Owners usually learn to recognize their cat's patterns and find solutions to aggression issues. If you've been dealing with an aggression problem for a long time, here are a few guides that may help you identify the cause of the aggressive behavior and find solutions:

But what about a sudden onset of aggression?

What to do when an otherwise loving non-aggressive cat suddenly turns on you, hissing and possibly even biting and scratching?

The first thing you need to check is... you guessed it, your cat's medical condition.

When in pain, even the friendliest cat may try to attack people around him. Just ask any veterinarian.

Sometimes the cat may be generally fine but react violently if you touch a painful spot. This doesn't even have to be a major medical issue - matted fur pulling on delicate feline skin can be enough to trigger a bite. Or it could be something more serious.

Other times, you may be dealing with re-directed aggression. Kitty may have been upset by something else inside your home - or out of it. Fear triggers aggressive behavior in some cats, and they sometimes get redirected to the nearest target around them.

If you suspect you may be dealing with re-directed aggression, read this guide:
Re-directed Aggression In Cats

"Why has my cat stopped using the litter box?"

There are many possible reasons for a cat to stop using the litter box. Generally speaking, they belong to one of three groups -

  1. Medical issues
  2. Problems with the litter box
  3. Stress

And yes, it can be a combination of reasons.

If your cat has stopped using the litter box, the first thing you need to do is schedule an appointment with the vet.

More often than not, there is a medical problem that's keeping the cat away from the box. Without solving that issue, you won't be able to re-train Kitty to use the box again.

Read more on how to figure out what's keeping your cat away from the litter box and how to solve the problem:
How To Solve Litterbox Problems In Cats: The Ultimate Guide

"Why is my cat acting strange after being outside?"

Injuries, disease, and parasites can all make your cat ill following a visit to the great outdoors. Cats that go outside can get into all sorts of trouble as follows:

  • Abscesses caused by catfights
  • Disease contracted from other cats
  • Fleas
  • Worms and other parasites
  • Fractures and other injuries
  • Stings and bites from small critters
  • Poisoning
  • Foreign objects lodged in various body cavities

If Kitty seems more distant or quiet after being outside, he or she may not be feeling well. Whether or not this was a regular outing, call your vet and get your cat checked out.

Final Words

As you may have noticed, almost any behavioral change could indicate a health problem. When a cat is sick, he or she cannot tell you as much. At least not in words. A sudden behavior change may be the only sign that the cat isn't well.

Talk to your veterinarian if you suspect a problem. Rule out medical causes and then explore behavioral options. And if you're not sure why your cat's behavior has changed all of a sudden, post your question in the cat behavior forum. That's where our members can try and help out.

If you can share a story about a sudden behavior change in your cat and how you solved the problem, please leave it as a comment below. Just remember—don't leave questions in the comment form. It may take too long for someone to see them here. Instead, post your questions in the cat behavior forum where others can see them and reply.


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17 comments on “Cat Acting Strangely? Here’s What It Could Mean

will July 29, 2023
I have Ferrell that's TNR, lives outside of my apartment in the woods and loves the wire brush but I can't hold her long. All the sudden she's scared to approach her food/house on my porch & I built her? Is this FDC or did someone put a deterent (like snake), sent or other anti-kitty something around my porch?
Michele October 6, 2022
I have an eight year old neutered male cat, he is a rescue that I’ve had for four years. He regularly goes to the vet. The strangest thing is that he left the yard of our home and my husband saw him in the street, this is after dark, he never leaves our backyard it’s a cats paradise. He came back home, my husband, and I ran down the street looking for him and a man had pulled over and asked if the orange cat was mine and I said yes, what’s the problem, and he said he was lying in the middle of the road . I thanked him for stopping and checking. I brought him home and I’m keeping him in the laundry room until I can see the vet tomorrow but wondering if anybody knows why this behavior change could be happening. I noticed this morning when I went to get him up he’s usually excited for breakfast but he never lifted his head and eventually and slowly he got up.
Denise June 1, 2022
Hi, So my cat has been different ever since I got my second cat (been 2 years now).I have taken him in since and they said he was fine. But I feel like something like snapped in his head. He eats but pushes it around the bowl and is chewing like extra to swallow. Even with crunchies! It’s super weird. I have to push his wet food into the middle of the bowl constantly why he’s eating. He’s healthy, his blood work came back ok his teeth are good. But now he’s crying more then usual. Like staring at me and crying. I’m gonna take him in but I just have a feeling they are gonna say he’s fine again and send me on my way. Does anyone have any ideas?
SpaceDuck April 14, 2021
hello! my cats have gotten along fabulously, and now one of them keeps getting bushy towards the other and chasing her around. i checked her all over, there's no injuries, i did notice she seemed a little stressed lately and currently have them separated for the day, is this normal or something to be alarmed over?
Melissa January 9, 2021
Hi my cat all the sudden starting breathing heavy and drooling after throwing up now I'm very concerned
Lynda Hamblen December 3, 2020
Hi, I love this article so much very helpful! As cats grow older, they tend to develop this behavior into a habit. More often than not, if your cat kneads, it just simply means they feel contented and relaxed.
Hilda Shumate May 2, 2020
I have a 2years old indoor female cat. She is sweet and well behave. One night she started running like crazy around the house. So fast and her face expression looked a little different. Everything else seems normal. Could it be that she got scared? Thanks
    AbbysMom May 2, 2020
    Hi Hilda! Why don't you start a thread in our Behavior forum? More people will see your question there.
Frank J Giuffre January 30, 2020
Hey all, I have a newly developing situation and I'm not sure how to handle it. To start, I live with four cats, one female and three male, all spayed/neutered. The female is the eldest at nine, then one male, and the last two males are about 2 and a half years old and from the same litter. Two things have started happening relatively recently. First, one of the cats from the same litter, Harry, has started to become aggressive towards our female at times, batting at her, while she hisses and either runs or fights back. This is the situation I think I understand best. Harry and his brother, Henry, were both very skittish cats. When I moved in with them, I began trying to socialize them immediately. Since then, Harry has become very social with people, enjoying playing, and pets. The more social he gets, the more aggressive he seems to get with the female though. Often, this doesn't seem to be related to her getting attention or anything. He'll just go after her while she's in the other room. The second situation involves Henry. He's still very skittish, letting me pet him occasionally, but not seeming to enjoy it or anything. Only in the last couple of months has he even begun taking treats from me(not from my hand yet). Recently, he's begun chasing around the other three, often to hissing and growling from the others. Even after these signs, he'll chase them or bat at them. I'm not really sure why this is happening. I'd really appreciate any advice or thoughts on my situation. No one has been hurt or anything, but I do worry about them. I'm really new to having cats, and these guys I kinda inherited, so I'm trying to learn as much as I can to take care of them as best as possible. Thanks in advance.
    AbbysMom February 1, 2020
    Hello! I'm so sorry you are having some issues. Please start a thread in the Behavior Forum. You won't get much help here in the comments forum but TheCatSite members will be able to give you advice in the Behavior forum.
    Furballsmom February 16, 2020
    Hi! We'd like to invite you to register with the site, and then post your question in the cat behavior forum which is where more members will see your situation and will provide you with advice and support. Here is the appropriate forum; Here is more information if you aren't familiar with forums;
    Furballsmom March 26, 2020
    Hi, Frank if you come back to TCS, register as a member and post your questions in the appropriate forum which would be Cat Behavior. Members will see your concerns, and provide you with suggestions and advice.
catsknowme July 21, 2018
Babypaws said:
I have a pregnant indoor cat who is due any day. She was a part feral cat that was born in our yard last summer and became pregnant, I was able get her to trust me and was able to bring her and her three kittens inside almost 8 weeks ago. But she was pregnant again and I didn’t know it. Suddenly she is turning against her 12 week old I’m worry she will hurt them once she has her new kittens.....before today she was a good this natural?? I guess I will have to keep them separate now.....I have two older cats that I’ve kept separate from these new cats until everyone has their shots... I feel like a referee...
Most ferals live multi-generational so I think the older kittens will stay away enough to remain safe. If you can manage it, a vet check is probably a good idea. Or at least be on stand-by during delivery. Is she on a good quality kitten food - she needs extra calcium & nutrition for a 2nd pregnancy (research hypocalcemia). I highly suggest starting a thread in the "Caring For Pregnant Cats and Kittens" forum - you will be mining the collective knowledge of both cat rescuers & breeders.
Babypaws July 21, 2018
I have a pregnant indoor cat who is due any day. She was a part feral cat that was born in our yard last summer and became pregnant, I was able get her to trust me and was able to bring her and her three kittens inside almost 8 weeks ago. But she was pregnant again and I didn’t know it. Suddenly she is turning against her 12 week old I’m worry she will hurt them once she has her new kittens.....before today she was a good this natural?? I guess I will have to keep them separate now.....I have two older cats that I’ve kept separate from these new cats until everyone has their shots... I feel like a referee...
catsknowme July 6, 2018
A very well-written guide!
PushPurrCatPaws June 29, 2018
This is a thorough and superb article! Thank you! :sunshine:

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