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Why Are My Cat's Eyes Red?

Red eyes can develop in cats due to disease, injury, infection, and other factors. Here, our South Florida vets define each of these causes in detail, how we diagnose these conditions, and which treatment options we may recommend. 

What We Can Learn From a Cat's Red Eye 

When you peer into your cat's eyes, you should normally see two clear, naturally colored peepers looking back at you. However, sometimes you may discover your kitty's eyes are irritated, red, or inflamed. 

Concerned clients sometimes ask our veterinary ophthalmologists why their cat's eyes would be red. We always reply that many potential health conditions, including disease, injury, infection, allergies, irritants, obstructions, or changes in the eyelids or eyelashes can cause eye discoloration. Swelling or inflammation may also develop. 

Each of these should be diagnosed and treated by a vet or veterinary ophthalmologist (what some may refer to as a "cat or dog eye doctor") right away to address symptoms and reduce or prevent the risk of long-term damage to your cat's eyesight. 

In this post, we'll explore how to tell if you think your cat may have an eye problem and the potential reasons your cat's eyes are red, before discussing diagnosis and treatment for this symptom. 

Does Your Cat Spend Time Indoors or Outdoors?

If your feline friend spends a significant amount of time outdoors, they'll be at higher risk of running into issues such as: 

  • Accidental pokes or scrapes 
  • Bees 
  • Grass 
  • Other animals 
  • Pollen 
  • Plants 

Though cats may jump at the chance to venture outside, these forays sometimes come at a cost to their safety. In addition, detecting the cause of your cat's red eyes can become more difficult if they've been outside among many potential sources of symptoms. 

What to Look For If Your Cat's Eyes are Red 

Some factors can point to what may be causing your cat's red eyes, and how serious the issue is. These include: 


The presence and color of any discharge can indicate how severe your cat's eye condition is. While an infection will commonly result in green or yellow discharge, bloody discharge can be caused by a serious injury. 

Excess tearing will often result in thinner discharge, while a buildup of mucus may lead to thicker discharge. 

Location of the Redness 

Are the tissues around your cat's eyes red, or so swollen that you're unable to see the eye itself? There may be a problem with the membranes around the eye (known as the conjunctiva). 

Conversely, if the whites of the eyes are inflamed and appear bloodshot, this issue may go away quickly (similar to how people's eyes sometimes appear bloodshot) with no serious cause. 

A third potential reason for redness: a third eyelid may be covering the eye. This whitish structure will cover the nose side of the eye at an angle to help shelter the eye when it's sore. If this membrane is raised, the eye's appearance may alarm those who look at it. 

What to Do If Your Cat Has Red Eyes 

Always book an appointment with your vet or veterinary ophthalmologist if you notice that your cat's eyes appear red. They'll be able to identify the cause of this concerning symptom and recommend treatment that may keep your cat from losing their vision, or potentially their eye. 

Discharge, swelling, or redness from the eye, along with being unable to open the eye, all qualify as veterinary emergencies. 

If your cat can open their eyes, the redness is mild, and your feline friend seems to be feeling well otherwise, you can likely wait up to 48 hours for an appointment with your veterinarian. If you aren't sure, contact your primary vet for advice. 

Common Causes of Red Eye in Cats

Many conditions can impact the appearance of your cat's eyes and their eyesight. While some of these issues concern the eye (globe) itself, others impact the tissue surrounding the eye. Conditions affecting the globe are typically more serious than conditions affecting the tissue. 


Because infections are always at risk of worsening, we recommend booking an appointment with your vet or veterinary ophthalmologist right away if you notice that your cat has a red eye. Bacterial or viral infections need to be treated and monitored as soon as possible. 


Also referred to as pink eye, conjunctivitis is the most common cause of red eye in cats. Typically the result of bacterial infection, conjunctivitis can also cause clear or dark fluid discharge, excessive winking, watery eyes, and swollen eye tissue. Your cat's eyes may also become extremely itchy and irritated. 

Injury or Trauma

If your cat spends time outdoors, they are more likely to get into fights with other animals. Even if they are exclusively indoors, too much roughhousing can cause injury or trauma due to scratches or bites, which can lead to redness. 

It's important to prevent injury or trauma from becoming infected and to get the proper treatment and diagnosis to reduce the risk of your cat's vision deteriorating. If you notice that your cat has a red eye or an eye injury, book an appointment with your vet right away. 

Chronic Diseases

Similar to other animals, cats are at risk of developing cancer and autoimmune conditions. Various cancers can affect your kitty's eyes, particularly feline lymphosarcoma-leukemia complex. Autoimmune disorders may lead to a condition known as uveitis, which can cause eye inflammation. 

Less Common Causes of Red Eye in Cats 

  • Allergies (e.g. dust, pollen, or bee stings)
  • Irritants (e.g. cigarette smoke, candles, air fresheners, or perfumes)
  • Obstructions (e.g. dirt or grass)
  • Glaucoma
  • Hyphema (bleeding into the front of the eye)

Diagnosing Red Eye in Cats 

It's important to see a vet or veterinary ophthalmologist if your cat as a red eye. While the symptoms for different causes are very similar, our team at Animal Eye Guys can run diagnostic tests to determine the specific eye condition causing the redness. 

We can also conduct a visual examination and may take fluid samples to test for pathogens. 

Treatment for Red Eye in Cats 

Veterinary ophthalmology involves the study, diagnosis, and treatment of eye diseases and disorders in cats and dogs. We also work closely with your pet’s primary care veterinarian to provide the best possible care for all ocular diseases that may be affecting your pet.

Once our board-certified veterinary ophthalmologist has determined what's causing your cat's red eyes, they can develop a treatment plan that may include: 

  • Medications such as antibiotics or other topical ointments such as eye drops to alleviate symptoms
  • Flushing the eyes with eyewash
  • Quarantining (for households with multiple cats, to keep the redness from spreading if your cat's eye condition is contagious)

Make sure to follow your vet's treatment recommendations and instructions carefully to avoid further eye injury or problems. 

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Do you suspect your cat may be experiencing redness, pain, or irritation in their eyes? Contact our South Florida veterinary ophthalmologists to book a consultation today.

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