Conjunctivitis in Cats (Cat Pink Eye)

Conjunctivitis in cats, also called cat pink eye, is a common eye condition that can cause swollen, pink eyes and drainage. It’s especially common in young cats that were recently adopted and often responds well to treatment with proper veterinary care.

What Is Conjunctivitis in Cats?

Conjunctivitis in cats, also known as cat pink eye, is inflammation of the conjunctiva, the mucous membrane that lines the upper and lower eyelids, including the third eyelid, and the eyeball.

Conjunctivitis in cats often occurs acutely (as a short-term condition) and can be painful. It's one of the most common eye diseases in cats.

What Are the Symptoms of Conjunctivitis in Cats?

Symptoms of conjunctivitis in cats can range from mild eye redness to more severe signs, including swollen eyes, discharge, excessive blinking, and squinting.

Eye symptoms may include:

• Inflamed or swollen conjunctival tissue
• Excessive blinking
• Squinting
• Difficulty fully opening or closing the eye
• Clear, mucous, or bloody discharge from the eye
• Itching around the eyes
• Hair loss around the eyes

Cats with conjunctivitis may also have signs of an upper respiratory infection (URI), including:

• Sneezing
• Nasal discharge, which may be clear or thick mucus
• Decreased appetite
• Lack of energy or lethargy

What Causes Conjunctivitis in Cats?

Conjunctivitis in cats can be caused by viruses, bacteria, parasites, immune-mediated conditions, allergies, physical irritants, tumors, and other eye diseases. Most cases of conjunctivitis in cats are viral. 

Viruses

Viral conjunctivitis may be caused by:

• Feline herpesvirus-1 (FHV-1). This is the most common cause of conjunctivitis, especially chronic or recurrent cases. The virus hides in the nervous system and activates at times of stress or illness.
  
  FHV-1 is similar to human herpesvirus-1, but this family of viruses is species-specific, so FHV-1 cannot infect humans. However, it's highly contagious to other cats in close contact.

• Calicivirus. This is another common virus. It's primarily shed in nose, eye, and mouth secretions, though it can be found in other body fluids. It's also spread through close contact. While many cats recover, others become lifelong carriers.

Bacteria

Cats with viral conjunctivitis may develop a secondary bacterial infection. Bacteria can also be the primary cause of conjunctivitis, although bacterial conjunctivitis is less common than viral conjunctivitis.

The most common bacterial pathogens include:

• Chlamydophila felis (C. felis)
• Mycoplasma
• Staphylococcus
• Streptococcus
• Bartonella
• Pseudomonas species

C. felis can cross species, although this is uncommon. Humans, particularly those with compromised immune systems, can catch it from infected cats.

Parasites

Outdoor cats are more prone to parasitic infections. These infections usually cause more systemic disease but can also cause conjunctivitis.

Parasites associated with conjunctivitis include:

• Leishmaniasis
• Thelaziasis
• Onchocerciasis

Humans may be susceptible to all three, but direct transmission is rare. Be aware of possible cross-species exposure and talk to a human-health professional if you have concerns.

Immune-Mediated Conditions

Immune-mediated conjunctivitis is uncommon and involves a cat's immune system attacking itself.

• Eosinophilic conjunctivitis is idiopathic in origin, meaning veterinarians don't know why it occurs. However, it may have a link to FHV-1. It causes an infiltration of a certain type of white blood cell to the conjunctiva, causing inflammation.
• Lipogranulomatous conjunctivitis occurs when lipids (fats) are deposited along the eyelid margin, glands, and ducts. Veterinarians are uncertain of the cause.

Allergies

Allergies can cause conjunctivitis in cats and may come from food or environmental factors, including:

• Dust
• Pollen
• Weeds
• Mites
• Fleas

Physical Irritants

Physical irritants that can cause conjunctivitis range from foreign bodies such as grass, sticks, or eyelashes to harder-to-identify irritants such as dust, chemicals, smoke, and eye ointments.

Tumors and Other Eye Diseases

• Ocular diseases such as ulcers, glaucoma, eye tumors, or eyelid malformations can cause secondary conjunctivitis.
• Eyelid diseases such as abnormal eyelid anatomy or cancer can cause frictional irritation or exposure that may lead to conjunctivitis.

How Is Conjunctivitis in Cats Diagnosed?

Veterinarians diagnose conjunctivitis in cats with a complete ophthalmic examination and may recommend additional testing to identify other eye diseases, infections, or underlying conditions.

Eye tests may include:

• A careful eye exam using special instruments and stains to look for other diseases in the eye.
• A Schirmer tear test to assess your cat's natural tear production.
• A fluorescein stain test to diagnose corneal ulcers.
• An intraocular pressure test to look for inflammation or glaucoma.

Blood tests may include:

• Testing for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). Cats with either virus are immunocompromised and therefore more susceptible to infections.
• Blood testing to look for signs of infection and assess overall organ function.

Additional testing may include:

• Radiographs (X-rays) to assess lung pathology, as cats with conjunctivitis frequently have respiratory infections.
• PCR, virus isolation, immunofluorescence antibody testing, and serology to test for specific bacterial and viral infections.

How Is Conjunctivitis in Cats Treated?

Treatment for conjunctivitis in cats depends on the underlying cause and focuses on eliminating pain and infection when present.

Topical eye drops or ointments may be prescribed, along with topical medications for inflammation and pain.

For infectious conjunctivitis: Your veterinarian may prescribe an antibiotic eye medication such as Terramycin or tobramycin. In some cases, combination antibiotic and anti-inflammatory eye drops, such as NeoPolyDex, may be prescribed.

For immune-mediated conjunctivitis: Immune-suppressive medications may be prescribed when needed. Prednisone acetate or tacrolimus may be recommended for cats affected by eosinophilic keratoconjunctivitis.

For viral conjunctivitis: Cats with viral conjunctivitis and severe herpes may be prescribed an oral antiviral medication such as famciclovir.

Your veterinarian will explain how to properly apply all eye medications, as great care is necessary to avoid further damage to your cat's eye.

Other infections will be treated on a case-by-case basis.

For immune-mediated conjunctivitis: Immune-suppressive medications may be prescribed when needed. Prednisone acetate or tacrolimus may be recommended for cats affected by eosinophilic keratoconjunctivitis.

For viral conjunctivitis: Cats with viral conjunctivitis and severe herpes may be prescribed an oral antiviral medication such as famciclovir.

Your veterinarian will explain how to properly apply all eye medications, as great care is necessary to avoid further damage to your cat's eye.

Other infections will be treated on a case-by-case basis.

Cat Conjunctivitis Recovery and Management

Most simple cases of conjunctivitis in cats resolve with seven to 10 days of topical therapy.

Certain infectious causes and immune-mediated cases may require longer treatment. If complications such as corneal ulceration or sequestration develop, outpatient surgery may be necessary.

Herpesvirus conjunctivitis: Herpesvirus is a common cause of conjunctivitis in cats from both rescue and breeder backgrounds. Herpes infections are sporadic and often first appear during kittenhood.

Many cats are infected with FHV-1 without showing signs of clinical illness. In most cases, herpesvirus conjunctivitis is self-limiting and resolves within two weeks, although the conjunctivitis should still be treated.

Signs of herpesvirus conjunctivitis may appear suddenly and are especially common after stressful situations such as travel, boarding, surgery, or illness.

During a flare-up, cats are more susceptible to secondary bacterial infections, which can be particularly concerning for young kittens.

How To Prevent Conjunctivitis in Cats

Good environmental hygiene, decreased stress, a low number of cats in the home, and early veterinary intervention can help prevent conjunctivitis in cats.

Probiotics and maintaining a stress-free environment may also help prevent viral conjunctivitis flare-ups.

Products your veterinarian may recommend include:

• FortiFlora: A probiotic product made by Purina that can decrease the severity of herpes conjunctivitis by utilizing "good" bacteria in the body.
• VetriScience Lysine Plus: An amino acid supplement that supports the immune and respiratory systems in cats.
• Hyaluronate-containing tear ointments or supplements, such as OphtHAvet Ophthalmic Solution Eye Lubricant: These products can provide lubrication and support the health of the eye's tears and glands. Healthy tear films can better clear and manage infections and associated inflammation.

For stress management, your veterinarian may recommend:

• Feliway: A pheromone product for multi-cat households that can decrease stress and therefore decrease the chances of viral conjunctivitis reappearing.
• Thundershirt: Uses calming, gentle pressure, similar to swaddling a baby, to help cats with anxiety.
• Prozac and similar prescription medications: May be helpful for cats with more severe anxiety.

While there is no cure for most causes of conjunctivitis in cats, there are many treatments and solutions available to effectively manage the condition and help cats live happy, healthy lives.

While there is no cure for most causes of conjunctivitis in cats, there are many treatments and solutions to effectively manage the condition and allow cats to live a happy, healthy life.