Cat Health

Understanding Dilated Cat Eyes: What It Means and When to Worry

cat with dilated eyes

Dilated cat eyes can be a fascinating and sometimes perplexing sight for pet owners. While it’s normal for a cat’s pupils to expand and contract in response to changes in light and their environment, there are times when dilated eyes might indicate something more.

Whether it’s a natural reaction to excitement or a sign of an underlying health issue, understanding the reasons behind your cat’s dilated pupils is crucial for their well-being.

In this post, we’ll explore the various causes of dilated cat eyes, what they might signify, and when you should consider seeking veterinary advice.

Normal Cat Pupils

Cats’ pupils change in size and shape in response to light and emotion. Typically, their pupils are vertical slits, indicating they are content and relaxed. However, when a cat is excited and ready to pounce, their pupils become round and large.

dilated cat eyes

What Causes Dilated Cat Eyes?

Low Light Conditions: The most common reason for dilated pupils is low light. Just like human eyes, a cat’s pupils dilate to allow more light in when it’s dark, helping them see better.

Excitement or Playfulness: During play or when they’re excited, cats’ pupils often dilate. This is a natural response to stimulation and heightened arousal.

Fear or Anxiety: When a cat is scared or anxious, their pupils may dilate as part of the fight-or-flight response. This helps them take in more of their surroundings.

Pain or Discomfort: Dilated pupils can be a sign of pain. If your cat’s eyes are dilated and they are displaying other signs of distress, such as hiding or vocalizing, it could indicate they are in discomfort.

TikTok user @echothebengal demonstrates how his pupils dilate before attacking a family member.

Medical Conditions That Cause Dilated Pupils

Several health issues can cause persistent pupil dilation, including:

Hypertension: High blood pressure (hypertension) can cause dilated pupils and symptoms such as weight loss, appetite changes, and poor coat quality. High blood pressure can be due to chronic kidney disease in older cats.

Eye Disorders: Glaucoma and uveitis can result in dilated pupils.

Progressive Retinal Atrophy (PRA): Cells that make up the retina start to die, which can lead to blindness and dilated pupils.

Glaucoma: Increased intraocular pressure results in wide pupils. It can affect one or both eyes and requires immediate veterinary attention.

Iris Atrophy: Thinning of the iris that appears as if there are holes in the iris structure. Usually, it affects only one eye (unilateral).

Ocular and Brain Tumors: Tumors affecting the eye structures or brain can trigger wide pupils. Based on the type of tumor, other signs are chronic pain, third eyelid changes, cat eye discharge, and cloudy eyes.

Anisocoria: Anisocoria is when the cat has uneven pupils or where one pupil is more dilated than the other. Anisocoria can be the result of corneal ulcers or head trauma.

Poor Vision: With age and other underlying conditions, a cat’s vision can deteriorate, leading to dilated pupils. A cat with poor vision is likely to squint a lot.

Feline Dysautonomia: A neurological condition that affects the autonomic nervous system and results in dilated pupils, respiratory symptoms and GI upset.

Image Credit: Example of anisocoria in a cat (Blumoon531, via Wikimedia Commons, CC BY-SA 4.0)


When To Seek Veterinary Care

While occasional dilation in response to changing light or emotional states is normal, there are times when dilated cat eyes warrant a trip to the vet:

  1. Persistent Dilation: If your cat’s pupils remain dilated for an extended period, especially in bright light, it could indicate an underlying problem.
  2. Other Symptoms: Look out for additional symptoms such as lethargy, vomiting, loss of appetite, behavioral changes like hiding more than normal, or signs of pain.
  3. Eye Abnormalities: If you notice any other abnormalities in your cat’s eyes, such as cloudiness, discharge, redness, or swelling, seek veterinary care promptly.
  4. Age-Related Changes: Senior cats are more prone to health issues that can cause dilated pupils, so regular vet check-ups are important.

What Will Happen At The Vet

Your veterinarian will perform a complete exam and order some testing to find out the underlying cause of your cat’s dilated eyes. This includes:

  • Baseline tests (bloodwork, urinalysis, blood pressure, etc.)
  • Ophthalmoscopy, to examine the retina, optic nerve, and blood vessels.
  • Tonometry, to measure the pressure inside the eye for glaucoma.
  • Ultrasound, to evaluate the eyes.
  • CT scan, to evaluate for brain tumors.

Vision Loss

When a cat starts to lose its vision, its eyes naturally dilate as they attempt to capture more light for visibility. If you observe abnormal behavior and notice any of these signs, your cat might be blind or on the verge of losing its sight.

Signs of vision loss in cats:

  • Hesitation to jump or climb
  • Squinting
  • Redness surrounding the eyes
  • Eyes appearing milky or cloudy
  • Displaying unsteadiness while walking
  • Struggling to locate water
  • Walking with whiskers close to the ground
  • Easily startled by sudden noises
  • Excessive vocalization, indicating distress


Ways To Check Your Cat’s Vision

You can easily assess your cat’s vision with these straightforward methods:

Swiftly move a laser pointer across the floor in front of your cat.

Toss cotton balls in their path; cats typically engage with them.

Gently wave your hand towards your cat’s eyes (without creating a breeze). Their natural response should be to blink.

Direct a bright light into their eyes; they should react accordingly.

How To Help A Blind Cat

In the event of your cat experiencing permanent blindness, there are steps you can take to assist:

  • Maintain the arrangement of furniture as your cat is accustomed to.
  • Communicate with your cat frequently in a calming manner.
  • Refrain from surprising your cat; announce your presence.
  • Ensure there are no obstacles obstructing your cat’s path.
  • Minimize exposure to loud noises to prevent distress.

grey cat with dilated cat eyes

Final Note – Dilated Cat Eyes

Dilated cat eyes can be a normal response to various stimuli, such as excitement, low light, or even certain emotions. However, persistent or unusual dilation may indicate an underlying health issue that requires attention.

Understanding the common causes and knowing when to seek veterinary care can help ensure your feline friend’s well-being.

By staying informed and observant, you can provide the best possible care for your cat and address any potential health concerns promptly. Always consult your veterinarian if you have any doubts about your cat’s eye health.

Dr. Georgina Ushi is a veterinarian and freelance medical writer. She received her Doctorate from the University of Florida College of Veterinary Medicine in 2009. She currently works in the Tampa Bay area, providing compassionate care to dogs and cats. Alongside her clinical work, Dr. Ushi consults for pet well-being brands and writes health articles for her blog, Pet Health Love. She is passionate about sharing her knowledge to educate and inspire fellow pet owners. Dr. Ushi’s professional interests include emergency and critical care, wildlife medicine, nutrition, and hospice and palliative care.

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