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.

There’s a Sudden Behavior Change in My Cat, Is It a Medical Issue? Signs to Watch For

cat scratching owner

Cats are fairly consistent animals and creatures of habit. While their personalities may change when they age from kittenhood to adulthood, most cats will sustain the same personality all throughout their lives. So, sudden behavioral changes don’t usually happen without reason. Various factors, including underlying medical issues, can affect a cat’s behavior. Here’s what to do if you notice a sudden change in how your cat behaves.

divider 2 cats

Behavior Changes and Medical Issues

Just like how we can act differently when we’re feeling uncomfortable, sick, or in pain, cats often change their behavior when they’re feeling unwell. Some cats will be very subtle, while others will make it more obvious. It really depends on how expressive your cat is naturally.

Cats can show a variety of behavioral changes when they’re sick. Some may become more lethargic or disinterested in playing. They might act more withdrawn and choose to hide more often than usual. They may hunch up or curl up and sleep more often. Cats can also show changes in appetite and either have increased or decreased hunger and thirst, depending on the medical condition.

While we may think that cats will slow down when they’re feeling sick, some medical conditions may cause them to appear more active. For example, hyperthyroidism may trigger hyperactivity in some cats. So, it’s important also to become curious and observant if your cat suddenly becomes active.

cat owner talking to his pet
Image Credit: Aziz Acharki, Unsplash

Other Signs That Your Cat Is Feeling Sick

Your cat will also give other cues that indicate that they’re feeling unwell. While it sounds unpleasant, make sure to check their litter box, as it can provide plenty of clues regarding your cat’s health. Discolored urine, diarrhea, and bloody stool all indicate health issues that require medical attention. More frequent litter box use, and painful urination or defecation are also signs of urinary tract infections or gastrointestinal issues.

Another way to detect health issues is to scan your cat’s physical appearance. Check for weight gain and weight loss and any changes in eating habits. Examine your cat’s coat. It should be smooth and well-kept. Cats that stop engaging in self-grooming habits or over-groom may be affected by a medical condition. If you notice any sudden behavioral changes in your cart, it’s best to take them to a veterinarian to get them checked out and make sure nothing is going on with their health.

divider 3 paws

Other Possible Reasons for Behavioral Changes

It’s recommended to schedule a visit with a veterinarian to determine if a medical issue is causing a behavioral change in your cat. If a veterinarian rules out any health issues, it’s important to figure out what else could be causing the behavioral change.

Your cat can start to act differently for a variety of reasons. Common reasons for shifts in behavior include moving to a new home, changing up their daily routine, or introducing a new cat to the home. Switching to new food or introducing your cat to new treats may also cause behavioral changes. It’s worth noting that cats that are bored and require more exercise and mental stimulation often begin to exhibit behavioral issues.

Usually, sudden lifestyle changes trigger sudden behavioral changes in cats. So, try to see if there’s anything new that may be causing your cat to act differently. If you’re having any trouble identifying triggers, don’t hesitate to work with a cat behaviorist to see how you can help 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

divider 2 cats

Conclusion

Sudden behavior changes in cats can be caused by a medical issue. However, changes to their environment or daily routine can also make cats act differently. As a general rule of thumb, take your cat to your veterinarian first to check for any health issues that may contribute to behavioral changes. If your cat’s physical condition gets the all clear, look around the house for any potential triggers that cause your cat to act differently.

Behavioral changes rarely happen without reason. Finding what’s causing these behavioral changes can help you create a safe living environment and satisfying daily routine that will lead to your cat feeling healthy and happy again.

See Also: 


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

One Response

  1. p'ease tell me a cat that has lived me since 2030 with her mom outside who never gives up for a chance to get her dinner, i have not seen her since friday night and i have never seen her not come eat. now it is sunday and no9 kitty. her mom comes but scatts as soon as she eats. that is not what she does.. i am so upset and i don"t know how to cope. please help me.

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.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Rushie the Special Needs Kitty: Rescued From the Streets of Dubai & Now an Internet Sensation

Watched by more than one million viewers, the story of Rushie is the sort of uplifting tale we all need to hear right...

My Cat Ate Styrofoam! Here’s What to Do (Vet Answer)

Some cats are determined to get into mischief and end up eating things they shouldn’t—food or otherwise! If you suspect your cat has...

How High Can a House Cat Jump? Highest & Average Jumps

Some cats are impressive athletes, while others prefer a leisurely nap that takes up most of the day. But most cats have impressive...

Why Is My Cat Quiet Suddenly? 5 Vet-Reviewed Reasons

Any change in feline behavior is potentially troublesome. Usually, changes in behavior are associated with illnesses and stress. These underlying causes range from...

More related

Cat Brain Anatomy: Vet-Verified Facts & Common Disorders

Anyone who knows a cat is familiar with just how different they act from humans. Sometimes, they do things that leave us feeling...

Do Cats Have Feelings? Feline Emotions Explained (Vet-Reviewed)

If you ask any pet owner, they’ll emphatically say that their cats have feelings. They say their cats have expressed love and affection,...

11 Ways to Keep Cats Out of Flowerbeds: Easy & Expert Tips

We all love our feline friends. They keep us company and even add beauty and elegance to our houses. But there are probably...

Silver Bengal Cat Breed: Info, Pictures, Origins & History

Silver Bengal cats are a type of Bengal cat with silver markings. These markings were introduced into some lines of the Bengal through...

Keep reading

Why Do Cats Like Bathtubs? 9 Possible Reasons (Vet Reviewed)

While it’s common knowledge that many cats don’t like water, it’s not uncommon for cats to spend time hanging out near bathtubs. They typically don’t like bathtubs that have much water in them, but some cats seem to have an...

a cat sitting in the bathtub

How Early Can You Hold a Kitten? Early Life & Vet-Reviewed Safety Tips

Cats are known to be exceptional at caring for their young ones, and there’s nothing more exciting than having a cat give birth to a litter of kittens at home. If you have a cat that has recently given birth,...

man-holding-kitten

Are Peonies Poisonous to Cats? Vet-Verified Risks & Safety Tips

Peonies have vibrant pink flowers and are popular plants, but pet owners have to consider more than just a plant’s beauty. Unfortunately, peonies are toxic to cats. If your cat has gotten into your peonies, then you need to get...

Catster_Are Peonies Poisonous to Cats

Can Cats Eat Animal Crackers? Vet Reviewed Facts

Picture the scene: You’ve stolen a few minutes to enjoy some animal crackers, and your cat comes over, settles at your feet, and gives you the “eyes” or a swipe at your hand if you’ve got a feisty feline. We...

Can Cats Eat Animal Crackers

Multiple Myeloma in Cats: Our Vet Explains Signs, Causes & Treatment

If you’re interested in multiple myeloma, your cat may have been recently diagnosed with this rare disease. If this is the case, we’re very sorry and understand you’ll want to know everything about the condition and what to expect moving...

sad, bored or sick cat

9 Best Cat Shampoos for Dandruff in 2025 – Reviews & Top Picks

While it’s an almost universal truth that shampooing your cat is not high on the list of fun activities, sometimes it can’t be avoided. If your cat has dandruff, they’ll be feeling itchy and scratchy. Choosing to bathe them using...

grey cat bath shampoo bubbles

10 Best Ringworm Shampoos for Cats in 2025: Reviews & Top Picks

Ringworm is an annoying fungal infection that our cats may develop from time to time, and even worse, it can spread to us. Getting rid of ringworm is vital to stopping its spread, and that’s where ringworm shampoos come in....

cat bathing in the bathroom

7 Best Cat Calming Supplements for Anxiety & Stress in 2025 – Reviews & Top Picks

There are plenty of reasons our pets can suffer from anxiety or stress. If you have a very skittish or stressed cat, you can buy supplements to help them alleviate their problem. These supplements don’t require a prescription, so you...

Scottish Cat with gold eyes takes a pill or medicine close up