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.

Why Are My Cat’s Eyes Dilated? 5 Vet-Reviewed Reasons & What To Do

Share

Havana Brown cat

If you’re a cat owner, you’ve probably noticed that your cat’s eyes sometimes get wide and dilated, like those of Puss in Boots from the “Shrek” movies. Although the big kitten eyes (a.k.a. dilated pupils) are normal in most situations, they can sometimes indicate a serious medical condition.

So, how do you know whether or not your cat’s dilated eyes are normal? Read on to learn more about the reasons behind the dilated pupils and when it’s necessary to seek veterinary attention.

divider 3 paws

The 5 Reasons Why Your Cat’s Eyes Are Dilated

1.  Excitement & Stimulation

Cats’ pupils dilate when they experience excitement or stimulation, such as during playtime. When felines play and pounce, their pupils dilate to let in more light, similar to what would occur in a genuine hunting scenario.

If your cat’s eyes dilate during mealtime or when they’re anticipating their favorite treat, it’s also a natural response. However, if your cat is frightened, angry, or surprised by something, their pupils can suddenly dilate. But don’t worry, they will return to their normal shape once the intense emotion has subsided.

american shorthair cat playing
Image Credit: MTS_Photo, Shutterstock

2.  Low-Light Conditions

Cats have the unique ability to see in low-light conditions. Their pupils naturally dilate in dimly lit areas, enabling more light to enter their eyes. That is why your cat’s eyes appear wider in the dark. The dilation of the pupils is entirely normal and helps the cat see better in the dark.

In total darkness, cats can’t see anything, just like humans! But even a tiny source of light, like a candle or moonlight, will help them find their way in the dark. Expanding and reducing the amount of light entering their eyes is vital for cats. Otherwise, they would not be the formidable nocturnal hunters that they are.


3.  Fear or Anxiety

When a cat becomes frightened or anxious, their pupils dilate as a part of their natural “fight or flight” response. However, if your cat’s eyes are frequently dilated, it may be wise to consult a veterinarian to ensure there are no underlying health or behavioral concerns.


4.  Pain

Dilated pupils in cats can be a sign of pain, even if the discomfort is mild. It’s essential to watch for other indications of pain, such as aggression or hiding, and promptly take your cat to see a vet if you suspect they’re in distress.


5.  Medical Conditions

It’s not normal for your cat to have permanently dilated eyes. Health conditions that can cause your cat’s pupils to be dilated include feline dysautonomia (also known as Key-Gaskell syndrome) and hypertension. Your cat can show other clinical signs, such as weight loss or gain, sudden loss of appetite, excessive thirst, difficulty urinating, vomiting, and diarrhea.

Dilated pupils can also be caused by poisoning from toxic plants, medication, or venomous animal bites. If your cat has unevenly sized pupils (one is dilated and the other is not), it could be a sign of a serious medical issue.

Conditions such as retinal disease, cancer, skull injuries, glaucoma, or neurological disease may be the underlying cause. Therefore, taking your cat to a veterinary clinic immediately is crucial if you observe this condition (called anisocoria).

vet checking a white cat's face
Image Credit: MakeStory Studio, Shutterstock

divider 3 paws

What to Do If You’re Worried About Your Cat’s Dilated Eyes

Unless your cat displays serious signs of illness or injuries or the dilation is prolonged, it’s more likely that excitement, playfulness, low lighting conditions, or temporary fear caused their dilated pupils.

It’s normal and healthy for your feline’s eyes to change and dilate throughout the day, but if you suspect that your cat’s dilated eyes result from a health problem, it’s best to contact your veterinary team without delay.

divider 3 paws

Conclusion

A cat’s pupils change depending on their mood and the lighting. If you catch your cat staring at you with big, dilated eyes, it’s usually a sign that something has caught their attention. However, if you notice that their pupils are consistently and excessively dilated, it’s vital to seek advice from a veterinarian to ensure your cat is healthy.


Featured Image Credit: slowmotiongli, 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

Chatting About the Importance of Spaying/Neutering, Cat Retail Shopping Ban & Red-Level Storms | Chatty Cattys, Episode 30

In this episode of Catster’s Chatty Cattys podcast, Nicole and Dr. Karyn are celebrating a major legal win for pets before diving into...

Is Your Cat Happy? Here’s How You Can Tell

Cats have a reputation for being indifferent, even inscrutable. But despite their seemingly ambivalent appearance, cats experience many emotions, including happiness, and they...

Human Brains Age Like Cats – New Study Debunks the 7-Year Rule

If you’ve ever caught your senior cat staring blankly at a wall, wandering the halls at 3 am, calling out for no clear...

Chatting with Devin About Here! Have a Kitten, Fostering, & Why Two Are Better Than One | Chatty Cattys, Episode 29

In this episode of Catster’s Chatty Cattys podcast, Nicole & Dr. Karyn sit down with Devin, the founder and one-woman show behind “Here...

More related

Keratitis in Cats: Causes, Diagnosis & Treatments (Vet Answer)

If you notice your cat squinting or has a discolored spot on the surface of their eye, take them directly to their veterinarian....

How to Stop a Cat From Killing Birds: 9 Vet-Reviewed Methods

Your house cat might seem like a big pushover when they’re snuggling on your lap, but those hunting instincts are often just below...

Do Cats Pee to Mark Territory? Vet-Reviewed Cat Behavior Explanation

If you’ve ever seen your cat back up to a wall, the couch, or anywhere that is a vertical surface and spray urine,...

Are Cats Playful? Vet-Reviewed Feline Character Explained

Absolutely, most cats love to play! However, cats vary a lot in temperament depending on their breed, gender, and other factors. Some breeds...

Keep reading

Why Do Cats Lift Their Tail When Petted? 4 Vet-Reviewed Reasons

If you have ever been petting your cat, you may have noticed that they lift their tail or bum in the air. There is a lot of confusion as to why cats do this and what the meaning behind the...

woman owner petting and playing with her cat at home

Cat Blood Types: How to Find Out (Vet-Approved Guide)

If you’ve ever given blood before or had surgery, you probably know your blood type. Humans have four blood groups—A, B, AB, and O. These groups can be Rh positive or negative, which means you can have one of eight...

vet sampling cat's blood

Can Cats Eat Pringles? Vet-Reviewed Facts & FAQ

Does your cat come running every time you pop open a can of Pringles because he loves the funny-shaped potato chips? If you’re wondering if cats can eat Pringles, you should know that Pringles and other chips aren’t good for...

Can Cats Eat Pringles

How Much Cat Litter Per Month Should You Use? Vet-Verified Facts & FAQ

There are many pleasant aspects of cat ownership, but litterbox duty isn’t among them. Still, it is essential to care for your cat, so ensuring that you provide the cleanest litter box possible for your pet is paramount. While litter...

cat sniffing litter in the box

Under the Sun Cat Food Review of 2026: Recalls, Pros & Cons

Review Summary Under the Sun cat food is produced by parent company Canidae. As one of the largest natural cat food brands, it’s focused on producing grain-free recipes containing no corn, wheat, and soy. Its balanced recipes contain a blend...

Under the Sun Review

Why Does My Cat Grab My Hand and Bite Me? 5 Vet-Reviewed Reasons

Cats are well-loved family members and can provide endless hours of entertainment, delight, and companionship. However, cats can also bite and grab your hand, which can be a shocking experience. We all can retract with a loud “ouch” when this...

tabby-cat-biting-the-hand-of-the-owner

5 Vet-Reviewed Tips on How to Use Cat Eye Drops (Without Getting Scratched)

Many cat owners are unsure how to handle the situation when their cat is diagnosed with an eye condition, and they’re prescribed eye drops. After all, it’s not like you can ask your feline pal to lean back their head...

treating-cats-eye

How to Cat Proof a Toilet Paper Holder: Vet-Reviewed Explanation & Tips

Cats are notorious for unraveling and shredding toilet paper, driving many a cat parent to despair. If your cat is wreaking havoc in the bathroom, it’s time to start looking into how you can cat-proof your toilet paper holders and...

mackerel tabby cat playing with roll of toilet paper

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.