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Feline Herpes Keratitis FAQ — Key Information Every Pet Owner Should Know

Eye HealthQ&AMeongsiljang Veterinary Advisory Board

Feline herpes keratitis is a viral eye condition in cats, making early detection and proper treatment essential. Here’s a summary of the key information every pet owner should know.

What is feline herpes keratitis?

A cat with red, irritated eyes and discharge

Feline herpes keratitis is an inflammatory eye condition caused by feline herpesvirus type 1 (FHV-1). It is particularly common in kittens, immunocompromised cats, and those living in shelters or multi-cat households. - Herpesvirus: The virus invades the eyes, nose, and throat, causing conjunctivitis and keratitis. While early signs may include mild redness and discharge, untreated cases can worsen, leading to corneal clouding or ulcers, such as dendritic ulcers. - Latent infection: Once infected, a cat remains a lifelong carrier. The virus lies dormant in the nervous system, such as in the trigeminal ganglion, and can reactivate during periods of stress, illness, or immunosuppression. - Risk of vision loss: Severe cases can result in decreased corneal transparency or scarring (fibrosis), potentially affecting vision. Early diagnosis is crucial, so please consult a veterinarian if you suspect symptoms.

Why do cats get infected with feline herpesvirus?

Feline herpesvirus is primarily transmitted through direct contact with an infected cat or via contaminated objects (fomites). - Direct contact transmission: The virus spreads when other cats come into direct contact with secretions from an infected cat’s eyes, nose, or mouth, or through social interactions such as grooming or rubbing heads. - Risk in group settings: In environments like animal shelters or homes with multiple cats, the increased opportunities for contact lead to faster transmission. - Latency characteristics: After initial infection, the virus remains dormant in the nervous system for extended periods and can reactivate when the cat’s immune system is compromised. - Potential for recurrence: Even cats that have been infected once may experience symptom flare-ups due to stress or illness. Early diagnosis and proper management are essential.

An infected cat in close proximity to another cat

What are the main symptoms?

The main symptoms of feline herpes keratitis include redness of the eyes, discharge, and squinting. You may notice excessive tearing, along with white or yellow mucous discharge. The cornea can become cloudy or develop white spots. If your cat is rubbing its eyes or having trouble opening them, immediate veterinary care is necessary. In some cases, fever, loss of appetite, and nasal discharge may also occur. If left untreated, the condition can worsen, leading to corneal ulcers and potential vision loss.

A cat’s eye with corneal clouding and conjunctival redness

Signs requiring immediate veterinary care

If your pet’s eyes are completely closed, if tearing increases, if the eyes appear cloudy, or if rubbing becomes severe, immediate veterinary care is necessary. Early treatment is essential because corneal ulcers or scarring can make vision recovery difficult. Extra caution is especially important for kittens, senior cats, and animals with weakened immune systems.

How is it diagnosed?

The veterinarian will first directly examine the condition of the eyes and, if necessary, assess for dry eye using a Schirmer tear test to measure tear production. However, the most reliable method for confirming a diagnosis of herpes keratitis is PCR (polymerase chain reaction) testing on tissue samples. Additionally, fluorescein staining may be performed to identify corneal ulcers, particularly the dendritic (branch-like) ulcers characteristic of herpes. Multiple tests are often conducted in parallel to ensure an accurate diagnosis.

A veterinarian examining a cat's eye with a slit lamp

What are the treatment methods?

Treatment primarily involves antiviral medications and tear substitutes. Topical antiviral eye drops (such as 0.1% idoxuridine) are typically applied every 4 to 6 hours. In severe cases, oral antiviral medications (such as famciclovir) may be used in conjunction. Corticosteroids are contraindicated because they can delay healing and deepen corneal ulcers; therefore, they must only be used under the strict guidance and direction of a veterinarian. If there is tear deficiency, artificial tears are necessary. Since antiviral agents suppress rather than completely eradicate the virus, the treatment course is prolonged, and ongoing management is required even after symptoms have resolved.

A veterinarian administering eye drops to a cat

How to prevent recurrence?

To prevent recurrence, it’s important to create a low-stress environment. Keep your cat’s daily routine consistent and gradually introduce them to new animals or environmental changes. A balanced diet and regular health check-ups are essential for boosting immunity. In some cases, preventive antiviral medication may be considered. If you have multiple cats in your home, isolation may be necessary to prevent the spread of infection.

Comparison of management strategies by symptom severity

Item	Mild	Moderate	Severe
Eye Congestion and Discharge	Mild congestion, clear discharge	Severe congestion, yellow discharge	Excessive tearing, cloudy cornea
Treatment Method	Artificial tears, observation	Antiviral medication, checkups twice a week	Antiviral medication, antibiotics to prevent secondary infection, intensive care including hospitalization
Frequency of Veterinary Visits	Recheck after 2-3 days	Daily or every other day	Daily monitoring

If symptoms worsen or do not improve within 48 hours, an immediate veterinary visit is necessary.

Precautions: Incorrect treatment can cause greater harm

Using medications without veterinary guidance or applying steroid eye drops on your own can worsen viral activation and lead to more severe eye damage. In particular, steroids are strictly prohibited if the eye becomes cloudy or if ulcers develop. Do not change or stop medications without your veterinarian's instructions. Consistency is key to successful treatment.

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 herpes keratitis be treated?

Yes, with early diagnosis and appropriate treatment, most symptoms can be well managed, and healthy cats may recover over the course of several weeks. However, since the virus can remain latent in the body and cause frequent recurrences, long-term management is necessary.

If a cat has pain in only one eye, could it be herpes?

Even if only one eye is affected, it could be herpes keratitis. However, herpes infections often affect both eyes early on, so it’s important to check both eyes and seek veterinary care promptly.

Can herpes viruses be transmitted to humans?

No, feline herpesvirus is species-specific and cannot be transmitted to humans. However, it is highly contagious among cats.

Are there any preventive vaccines?

Although a herpesvirus vaccine is available, it doesn’t provide complete protection, as vaccinated cats can still develop herpes-related symptoms such as conjunctivitis. However, the vaccine can help reduce the frequency and severity of these symptoms.

What should I do if the condition keeps coming back frequently?

If the condition keeps recurring, it’s a good idea to work with your veterinarian to develop a long-term antiviral treatment plan. Managing stress and boosting your pet’s immune system are also important.

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References

[1] Ofri R. Conjunctivitis in cats. NAVC Clin’s Brief 2017 (April):95-100.

[2] Plummer CE. Herpetic keratoconjunctivitis in a cat. NAVC Clin’s Brief 2012; January:26-8.

[3] Nasisse MP, Davis BJ, Guy JS, Davidson MG, Sussman W. Isolation of feline herpesvirus 1 from the trigeminal ganglia of acutely and chronically infected cats. J Vet Intern Med 1992;6(2):102-3.