If Your Cat Keeps Rubbing Its Eyes — Symptoms and Lifelong Management of Herpetic Conjunctivitis

Eye HealthDiseasesMeongsiljang Veterinary Advisory Board

We’ve compiled a comprehensive overview of feline herpesvirus (FHV-1), the most common cause of conjunctivitis in cats, covering its characteristics, symptoms, treatment, and lifelong management of recurrences, all based on veterinary ophthalmology standards.

What Is Feline Conjunctivitis?

Illustration: Overview of Feline Conjunctivitis Definition and Herpes Virus Etiology

Feline conjunctivitis is an eye condition characterized by inflammation of the conjunctiva, the thin mucous membrane lining the inner eyelids and covering the surface of the eyeball. In cats, the most common cause of infectious conjunctivitis is Feline Herpesvirus Type 1 (FHV-1). Once infected, the virus can remain latent in the nerves, such as the trigeminal ganglion, for life and may reactivate during periods of stress or immune suppression, leading to recurrence. What truly matters is early treatment and lifelong management. If symptoms like redness, discharge, or frequent eye rubbing persist for more than 24 hours, seek veterinary care immediately.

Causes and Pathogenesis

The leading cause of conjunctivitis in cats is the feline herpesvirus (FHV-1), followed by Chlamydophila felis, Mycoplasma, and calicivirus. Among these, herpesvirus often causes initial infection during kittenhood. Once infected, the virus remains latent in the trigeminal ganglion for life. It can reactivate and trigger recurring conjunctivitis episodes during periods of significant stress—such as moving, introducing new cats, hospitalization, or surgery—or when the immune system is compromised by other illnesses.

Key Symptom Checklist

Herpetic conjunctivitis often starts in one eye and may later affect both. If you notice two or more of the following signs, conjunctivitis should be suspected: - Redness and conjunctival swelling (chemosis): The white part of the eye becomes red, and the conjunctiva swells. - Increased discharge (crusting and tearing): There is more tearing or crusting around the eyes. - Frequent blinking or squinting (blepharospasm): This indicates pain and irritation. - Light sensitivity (photophobia), sneezing, and nasal discharge: These may occur alongside an upper respiratory infection (URI). - Rubbing the eyes with paws (pawing): This behavior increases the risk of corneal damage.

A close-up of one eye of a cat showing conjunctival redness and discharge.

Seek Immediate Veterinary Care for These Signs

Herpesvirus can spread beyond the conjunctiva to invade the cornea. Seek emergency care if you notice any of the following signs: - A bluish or grayish cloudiness in the eye (possible corneal ulcer) - Inability to open the eyes due to pain, leading to refusal of food and water - Yellow or green purulent discharge persisting for more than 48 hours - Both eyes stuck shut and unable to open in kittens If a corneal ulcer progresses, it can lead to permanent vision loss or even perforation of the eyeball.

How Is It Diagnosed?

At the veterinary clinic, we first use a slit lamp to closely examine the conjunctiva and cornea, and perform a fluorescein stain test to check for corneal injuries (ulcers). Herpes is characterized by dendritic ulcers, so the stain alone can strongly suggest the diagnosis. To accurately identify the causative agent, we conduct PCR testing on a conjunctival swab sample. This test allows us to differentiate between herpes, chlamydia, and mycoplasma in a single analysis, enabling us to tailor the treatment medication precisely.

Treatment — Stepwise Approach by Cause

Treatment depends on the causative pathogen and whether the cornea is involved. - Herpes conjunctivitis and keratitis: Topical antiviral agents such as trifluridine, idoxuridine, and cidofovir are used. However, in cases of conjunctivitis alone without corneal involvement, the efficacy of antiviral agents varies among individuals. - Secondary bacterial infection: Broad-spectrum antibiotic eye drops are prescribed concurrently to control secondary bacterial infections. - Suspected other causes, such as Chlamydia: The veterinarian will determine the appropriate type and regimen of antibiotics based on diagnostic results. - Corneal ulcer present: Referral to a veterinary ophthalmologist may be necessary. L-Lysine supplements are sometimes used, but a 2015 systematic review found no evidence supporting their efficacy, and there are concerns that they may even worsen symptoms or increase recurrence rates in some cases. Therefore, always consult your veterinarian before administering L-Lysine, and do not discontinue prescribed antiviral medications without a follow-up examination.

A caregiver’s hand applying eye drops to a cat

Home Care Essentials

With herpes, managing stress is essentially managing recurrences. Please keep the following five points in mind on a daily basis: - Keep the eye area clean: Gently wipe away discharge with gauze moistened in lukewarm sterile saline (do not use wet wipes or paper tissues). - Separate cats in multi-cat households: During symptomatic periods, provide separate food bowls and litter boxes. - Maintain a comfortable environment: Preventing the environment from becoming too dry helps reduce irritation to the mucous membranes. - Schedule introductions, moves, and visits carefully: Avoid overlapping stressful events such as new companions, moving, or unfamiliar guests. - Use lysine supplements cautiously: Since evidence regarding its efficacy is inconsistent, always consult your veterinarian to determine whether to use it and at what dosage, and do not increase the amount on your own.

Lifelong Recurrence Management — Key Points for Owners

Feline herpesvirus never fully leaves the body; instead, it remains latent for life in the trigeminal ganglion. When a cat experiences stress or a weakened immune system, the virus can reactivate and cause conjunctivitis to recur. Kittens that suffer severe infections may develop chronic conjunctivitis or chronic nasal discharge that persists into adulthood. Even with vaccination (the standard FVRCP vaccine covering herpesvirus, calicivirus, and panleukopenia), herpesvirus-induced conjunctivitis can still occur. While vaccines do not completely prevent infection, they help manage symptoms, so please keep up with regular boosters. For safety, isolate any new cat for two weeks before introducing it to your household.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can feline conjunctivitis be transmitted to humans?

Feline herpesvirus (FHV-1) is highly species-specific and does not transmit to humans. However, Chlamydia can rarely cause conjunctivitis in people, so please be sure to wash your hands thoroughly after touching your pet's eyes.

Do I need to give lysine supplements to my pet for life?

For dogs with frequent recurrences, long-term medication is sometimes recommended, but recent studies have raised questions about its effectiveness. It’s best to consult your veterinarian and decide based on the frequency of flare-ups and the severity of symptoms.

What should I do if only one cat in a multi-cat household has conjunctivitis?

Isolate infected cats in a separate area and use dedicated bowls, litter boxes, and toys for them. To reduce the risk of cross-infection, always wash your hands after handling an infected cat before touching other pets.

My pet refuses eye drops. How can I administer them?

Gently wrap your pet in a towel, positioning your hand behind their head to prevent them from seeing the eye drops. Immediately offering praise and a treat after administration will make the next application much easier.

Once infected, does it truly last for life?

Yes, FHV-1 remains latent in the trigeminal ganglia for life. However, by managing stress, keeping up with regular vaccinations, and seeking early treatment, you can significantly reduce both the frequency of recurrences and the severity of symptoms.

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References

[1] Esson DW, Calvarese S. Clinical Atlas of Canine and Feline Ophthalmic Disease, 2nd Ed. Wiley, 2022 — Chapter 58: Herpesviral-associated Conjunctivitis

[2] Schaer M, Gaschen F. Clinical Medicine of the Dog and Cat, 4th Ed — Feline Chlamydiosis & Respiratory Tract

[3] 100 Top Consultations in Small Animal General Practice — Conjunctivitis section

[4] The Veterinary Workbook of Small Animal Clinical Cases — Kitten Wellness Examination