CatsMedical & Health

Red eye in cats is a serious medical problem causing blindness

Red eye in cats is a symptom of an underlying disease

Red eye in cats is a serious medical problem that can worsen over time, causing blindness and further destroying the eye structure. Red eye in cats is a symptom of an underlying disease, eye irritation, or a cat eye injury. The red colour of one or both eyes indicate that cats have an unknown health condition that must be treated by a specialized veterinarian.

If you notice red eye in cats, she might have experienced trauma to the eye, an allergy or irritant, a viral infection such as distemper, a bacterial infection, glaucoma, cherry eye or cancer.

What are the symptoms accompanying red eye in cats?

The rather obvious symptom of red eye in cats is, in fact, a red coloration of the eye. Depending on the source of the red eye condition, your feline may or may not experience the following additional associated symptoms:

  • The whites of the eyes become reddened 
  • Swollen eyes
  • Swollen eyelids 
  • Eye discharge (clear, white, yellow or green in coloration) 
  • Tearing of the eyes
  • A protruded third eyelid (cherry eye)

Learn about third eyelid in cats Red eye in cats

  • Rubbing the eyes 
  • Itchy eyes
  • Inability to open the eye
  • Loss of sight
  • Sneezing
  • Watery eyes
  • Coughing
  • Painful eyes

Regardless of the severity of the signs, the eyes are very sensitive structures and any change in their appearance requires immediate veterinary examination.

What are the causes of red eye in cats?

A feline’s eyes can become red for several reasons. Trauma, allergies, obstructions, structural changes of the eye, disease, viral infections, bacterial infections, and irritants can all cause the eye of a cat to become red. The most Red eye in catscommon causes of red eye in cat include:  

Trauma :Red eye in cats

  • Scratches
  • Bites
  • Pokes 
  • Allergens
  • Pollen
  • Dust
  • Bee stings

 Irritants:Red eye in cats

  • Cigarette
  • smoke 
  • Perfumes
  • Air fresheners


  • Seedling
  • Grass seeds
  • Dirt

  Structural Changes:

  • Entropion (eyelid protrudes inward)
  • Ectropion (eyelid protrudes outward)
  • Distichiasis (abnormal eyelash growth)


  • Cancer
  • Autoimmune disease

Bacterial Infection:

  • Chlamydia
  • Mycoplasma 

Viral Infections:

    • Feline herpesvirus type 1
    • Calicivirus
    • Feline immunodeficiency virus (FIV)

Diagnosing red eye in cats

Red eye in catsYour veterinarian will perform a complete physical exam on your cat, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel. You will need to give a thorough history of your cat’s health, an onset of its symptoms, and possible incidents that might have precipitated this condition.

Red eye in cats is often a visible symptom of an underlying systemic disease, sometimes of a serious nature. Consequently, bloodwork is essential for ruling out or confirming an underlying disorder.

In order to rule out cancer and infectious causes to the red eye, X-ray imaging can be used for visual inspection of the chest and abdomen. Just as useful for diagnostic purposes are ultrasound images of the eye, which can be performed if the eye is opaque, and tonometry — measurement of the pressure inside the eyes using a tonometer.

If there is pus-like discharge from the eye, or long-term disease of the eye, your veterinarian will perform an aerobic bacterial culture and sensitivity profile.

Other tests your veterinarian may choose to perform are a Schirmer tear test, used to verify normal tear production; a cytologic (microscopic) examination of cells from the eyelid, conjunctiva, and cornea; and a conjunctival biopsy (tissue sample) if there is chronic conjunctivitis or mass lesions.

For cats, a polymerase chain reaction (PCR) test can be used for diagnosing a hereditary or infectious disease, or an indirect fluorescent antibody (IFA) test of scrapings from the cornea or conjunctivae can be used to test for herpes virus and Chlamydia bacteria, both of which can indirectly affect the eye.

Fluorescein staining of the cornea, which uses a non-invasive dye to coat the eye, making abnormalities more visible under light, can also be used for the detection of foreign material, ulceration, scratches, and other lesions on the surface of the cat’s eye.

How to treat red eye in cats?

  • Red eye in catsSince most cases of red eye in cats are more sensitive to bright light, keep your pet indoors during the day and dim internal lights. If your pet’s vision is affected, they may need help locating food and water.
  • Take medication as directed by your veterinarian
  • Each case causing the red eye is treated differently.
  • For bacterial or allergic eye disease, a triple steroid antibiotic ointment is usually prescribed.
  • The underlying allergy must also be treated.
  • In cases of corneal ulcers, anti-bacterial drugs without steroid are used to prevent infection while the ulcer heals.
  • In cases of glaucoma, medications that increase eye drainage and reduce pressure in the eyeball, including dorsolamide and timolol, are prescribed.
  • In cases of uveitis, medications are prescribed based on the cause of the iritis.
  • In KCS cases, the drug will be prescribed to help increase tear production, such as tacrolimus.
  • If the pupil suffers from severe distress due to pain, atropine can be used to expand the pupil.
  • Pain medications may also be prescribed orally if the pet is uncomfortable.
  • If your cat’s eye has a foreign object in the eye, the vet will often need to sedate your pet to remove the object.
  • In most cherry cases, surgical replacement of the drooping gland is necessary.
  • Some cases may be referred to a veterinary ophthalmologist


Depending on the situation, your pet can fully recover with appropriate treatment. In some cases, cats with chronic eye conditions often have red eyes if their condition worsens.

The cat may need to wear an Elizabethan collar around its neck at home to prevent scratching the eye and causing additional damage. Your vet may also order a home humidifier to remove irritants that may affect cats.


The vet will schedule the re-checkups based on your pet’s condition.


Bacterial conjunctivitis may spread to other pets. In this case, separating the infected pets from one another may help limit the spread. Other causes may not be prevented.


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