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

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.

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


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

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.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Anisocoria in Cats: Causes & Care Guide (Vet Answer)

Cats are known for their beautiful eyes. They even have special pupils that change shape! When fully open (dilated), their pupils are round,...

Example of Horner's syndrome in a cat

Do Cats Like the Dark? Vet-Verified Vision Facts (With Infograph)

All cat parents know that their adorable feline turns into a formidable predator when night comes. Frantic runs all over the house at...

cat with spotlight beside a book on the table

Cat Pupils: Eye Meaning Explained (Vet-Verified)

The proverb “The eye is the window to the soul,” is fitting when it comes to cats. They use it to communicate a...

Chocolate point doll faced himalayan cat

10 Facts About Cats’ Eyes: Vet Verified

We sometimes wonder if our cats see the world the same way we do. Are cats’ eyes similar to humans? Do they work...

devon rex with blue eyes

More related

Cat with third eyelid

What Is a Cat’s Third Eyelid & What if It’s Showing? Vet Approved Advice

Cats have a unique anatomy. For instance, did you know that cats have not one or two eyelids, but three? It’s true! A...

Dilute Tortoiseshell cat

Can Cats Have Brown Eyes? What Science Tells Us

If you’ve spent time with cats or have cats of your own, you’ve likely noticed that there are a handful of prevalent eye...

Cat with red, swollen an inflamed gums or resorption of teeth in felines and gingivitis showing teeth

Why Are My Cat’s Gums Red and Swollen? 8 Possible Reasons & What to Do

Owning a cat has its ups and downs, and unfortunately, most of the downs occur when our pets are sick. When your cat...

What Is Cat “Rust”? Causes & What to Look Out For (Vet-Verified Info)

Black cats have long been associated with bad luck, but their luck has changed significantly in the last few decades. With the rise...

Keep reading

How to Calm a Stressed Cat After Moving: 17 Vet-Verified Tips

Did you know that moving is considered one of the most stressful life events humans can go through? It’s true, but it’s not just us that moving impacts. Our pets can be extremely stressed out by the entire process, and...

woman-petting-her-cat

8 Products for Senior Cats to Make Your House Easier for Them

It seems that one minute, you have a sprightly little kitten jumping around, ripping down your curtains, and the next, you have a lazy old senior who prefers taking window naps. Our animals’ lives certainly go far too quickly for...

Long hair tabby cat with beautiful green eyes and long whiskers stretched out and relaxed senior cat

What Is Cat Middening? Vet-Reviewed Causes, Prevention & FAQ

Life is always interesting when you have a cat in your life. But one of the more trying issues for cat parents is when your cat urinates and/or defecates outside the litter box. When a cat poops outside of their...

cat-pooping-outside-the-litter-box

Why Is My Cat Breathing Fast? 5 Reasons Behind This (Vet Answer)

A cat that seems to be breathing faster than usual is always alarming and should be checked by your vet straight away. After all, any change from the ordinary often signals an underlying problem, particularly when it comes to breathing....

manx-lying-on-the-floor

Are Laser Pointers Bad for Cats? Vet-Approved Safety Information & Tips

Laser pointers are popular toys, and it can be fun watching your cat chase after that little red dot. But if you’re wondering whether laser pointers are safe for cats, the short answer is that laser pointers are controversial because...

Two cats are lying on the floor. Gray cats are playing with a laser pointer.

10 Warning Signs Your Cat Is Crying for Help: Vet-Reviewed Facts & FAQ

How do you know when your enigmatic feline companion needs help if there’s no actual “crying” involved? Should you take a wait-and-see approach or head straight to the emergency veterinary clinic? It’s not always easy, but by paying attention to...

Sick sad cat lying on the bed

How Much CBD Oil Should I Give My Cat for Anxiety? Optimal Dosing Chart

CBD has exploded in popularity recently, being touted as a miracle cure for a wide range of ailments that’s supposedly a more natural alternative to many pharmaceuticals. But CBD isn’t just for people. More and more CBD products are being...

cbd oil and cat on background

Evanger Cat Food Review in 2025: Reviews, Pros & Cons

Review Summary At first glance, this brand looks very high-quality. It is a bit more expensive, but you’re paying for extra meat and novel ingredients. Many of the formulas are high in protein and nutritious ingredients. However, this brand has...

Evanger's Review