Last updated: March 25, 2026

Feline Herpesvirus: Symptoms & Management

Feline herpesvirus type 1 (FHV-1) is one of the most widespread viral infections in domestic cats. By some estimates, up to 90 percent of cats have been exposed to this virus at some point in their lives, and the majority carry it for life in a dormant state. For many cat owners, the first encounter with FHV-1 comes when their cat develops recurring eye or respiratory symptoms that seem to appear out of nowhere, resolve with treatment, and then return weeks or months later. Understanding this virus — how it works, what triggers flare-ups, and how to manage it — is essential for any cat owner dealing with its effects.

FHV-1 belongs to the same broad family of herpesviruses that cause cold sores in humans, though the feline and human viruses are completely different species and cannot cross-infect. Like its human relative, FHV-1 establishes a lifelong latent infection in nerve tissue after the initial illness. The virus hides in the trigeminal nerve ganglion, a nerve cluster near the base of the skull, where the immune system cannot reach it. Periodically — often triggered by stress — the virus reactivates, travels back along the nerve fibers to the eyes and upper respiratory tract, and causes another round of symptoms.

What Is Feline Herpesvirus?

Feline herpesvirus type 1 is a double-stranded DNA virus in the family Herpesviridae. It is the primary cause of feline viral rhinotracheitis (FVR), one of the two major components of upper respiratory disease in cats, the other being feline calicivirus. FHV-1 specifically targets the tissues of the upper respiratory tract — the nose, sinuses, throat, and trachea — as well as the conjunctival membranes of the eyes.

The virus is highly contagious among cats and spreads through direct contact with infected secretions (nasal discharge, saliva, eye discharge) or through contaminated objects such as food bowls, bedding, and human hands. It can survive in the environment for up to 18 hours under favorable conditions but is easily killed by common disinfectants. Cats are most infectious during active illness, but latently infected cats can also shed virus during reactivation episodes, sometimes before symptoms become apparent.

Kittens and immunocompromised cats are most vulnerable to severe primary infections. In adult cats with healthy immune systems, the initial infection is usually self-limiting, though uncomfortable. The real challenge with FHV-1 is its lifelong persistence and the potential for repeated flare-ups that affect quality of life.

Causes and Transmission

Primary FHV-1 infection occurs when a susceptible cat is exposed to the virus, typically through direct contact with an infected cat or contaminated fomites. The most common transmission scenarios include shelter environments where cats are housed in close proximity, multi-cat households where new cats are introduced without proper quarantine, breeding facilities, and veterinary clinics or boarding facilities where infected and susceptible cats may share space.

Kittens are most commonly infected between two and six months of age, after maternal antibodies from nursing begin to wane. Shelter-acquired kittens have particularly high infection rates — some studies report FHV-1 prevalence exceeding 50 percent in shelter cat populations. If you have recently adopted a cat from a shelter or rescue, awareness of FHV-1 is important even if your cat appears healthy at the time of adoption.

After the primary infection resolves, the virus establishes latency in the trigeminal ganglion. Reactivation can be triggered by physiological or psychological stress, including changes in environment or routine, introduction of new animals, boarding, veterinary visits, surgery, concurrent illness, pregnancy or lactation, corticosteroid administration, and even seasonal temperature changes. Not all cats reactivate at the same frequency — some rarely or never show symptoms again, while others experience frequent flare-ups. The individual immune response appears to determine the pattern.

Symptoms of Feline Herpesvirus

Primary infection. The initial infection typically produces an incubation period of two to six days, followed by acute upper respiratory symptoms lasting one to three weeks. Clinical signs include sneezing (often frequent and forceful), clear to mucopurulent nasal discharge, conjunctivitis with eye discharge, fever, lethargy, decreased appetite, and drooling. Kittens may develop severe disease with high fevers, pneumonia, and oral ulcers. In very young or immunocompromised kittens, primary FHV-1 infection can be life-threatening.

Recurrent episodes. Reactivation episodes are typically milder than the primary infection. Symptoms may include mild sneezing, one-sided or bilateral eye discharge, conjunctival redness, corneal involvement (keratitis), and occasionally nasal congestion. Episodes usually last one to two weeks and may or may not require treatment depending on severity.

Ocular complications. FHV-1 has a particular affinity for the cornea, and eye complications are among the most significant long-term consequences of infection. These include dendritic corneal ulcers (branching ulcer patterns that are virtually pathognomonic for herpesvirus), stromal keratitis (deep corneal inflammation), corneal sequestration (a dark, necrotic area on the corneal surface), symblepharon (adhesion of conjunctival tissue to itself or the cornea), and keratoconjunctivitis sicca (dry eye). Severe or recurrent ocular disease can lead to permanent corneal scarring and vision impairment.

Chronic rhinosinusitis. Some cats develop chronic nasal congestion, sneezing, and nasal discharge that persists between active viral episodes. This occurs because the initial viral damage to the nasal turbinate bones creates an environment susceptible to chronic bacterial infection and inflammation. These cats may have perpetually noisy breathing and thick nasal discharge.

Diagnosis of Feline Herpesvirus

Diagnosis of FHV-1 is often based on clinical signs and history, but specific diagnostic tests are available when confirmation is needed.

Clinical diagnosis. In many cases, the combination of upper respiratory symptoms, conjunctivitis, and a history of shelter exposure or multi-cat housing is sufficient for a presumptive diagnosis. The pattern of recurrent episodes with stress-triggered flare-ups is highly suggestive of FHV-1.

PCR testing. Polymerase chain reaction (PCR) testing on conjunctival or nasal swabs can detect FHV-1 DNA with high sensitivity and specificity. A positive result during active symptoms confirms that the virus is replicating. However, latently infected cats may test negative between episodes, so a negative PCR does not rule out FHV-1 as the underlying cause of recurrent disease. Some cats also shed virus asymptomatically, so a positive PCR in a cat without symptoms does not necessarily mean the virus is causing their current problem.

Fluorescein staining. When ocular involvement is suspected, fluorescein staining of the cornea can reveal the characteristic dendritic (branching, tree-like) ulcer pattern that is essentially diagnostic of herpesvirus keratitis. This simple in-office test provides immediate, actionable information.

Virus isolation. Growing the virus in cell culture is highly specific but slow (results take days to weeks) and has low sensitivity because the virus is fragile and may not survive transport to the laboratory. This method is rarely used in clinical practice.

Serology. Measuring antibodies against FHV-1 in the blood has limited diagnostic utility because most cats have antibodies from vaccination or previous exposure, making it impossible to distinguish past from current infection.

Treatment of Feline Herpesvirus

There is no cure for FHV-1 — the virus cannot be eliminated from latently infected cats. Treatment focuses on managing acute episodes, reducing symptom severity, and preventing complications.

Antiviral medications. Famciclovir is the most widely used systemic antiviral for FHV-1 in cats. It is administered orally, is well-tolerated, and has demonstrated efficacy in reducing viral shedding and clinical symptoms. The typical dose is 90 mg/kg every eight hours, though your veterinarian will determine the appropriate regimen. Topical antiviral options for ocular disease include cidofovir ophthalmic drops and idoxuridine or trifluridine ophthalmic solutions. These must be applied frequently — often every four to six hours — which can be challenging for both cat and owner.

Antibiotics. Antibiotics do not treat the virus itself but are prescribed when secondary bacterial infections develop, which is common. Doxycycline is often chosen because it is also effective against Chlamydophila and Mycoplasma, common co-pathogens. Broad-spectrum ophthalmic antibiotic ointments may be used to prevent secondary bacterial infection of damaged ocular tissues.

Supportive care. Maintaining hydration and nutrition during acute episodes is critical, particularly in kittens. Nasal congestion can reduce a cat’s ability to smell food, leading to appetite loss. Warming food to enhance aroma, offering strong-smelling foods like fish-based diets, using a humidifier to loosen nasal secretions, and gently cleaning discharge from the nose and eyes with warm, damp cloths can all help. Severely affected cats may need hospitalization for intravenous fluids, nutritional support, and nebulization therapy.

L-lysine supplementation. For many years, L-lysine was widely recommended to reduce herpesvirus replication. The theory was that lysine would compete with arginine, an amino acid essential for herpesvirus replication. However, multiple well-designed studies have failed to demonstrate a clinical benefit, and some research suggests lysine supplementation may actually worsen outcomes by reducing arginine levels. Most veterinary specialists no longer recommend routine lysine supplementation for FHV-1.

Interferon therapy. Feline recombinant interferon omega has shown some promise in reducing symptom severity when applied topically to the eyes or administered systemically. It is more commonly available in Europe and Japan than in North America.

Prevention of Feline Herpesvirus

Prevention strategies focus on reducing exposure and maintaining immune competence, since complete prevention of FHV-1 infection is impractical given its prevalence.

Vaccination. The FHV-1 vaccine is part of the core feline vaccination protocol (the FVRCP combination vaccine). Vaccination does not prevent infection but significantly reduces the severity of disease if the cat is exposed. Kittens should receive their initial vaccine series starting at six to eight weeks of age, with boosters as recommended by your veterinarian. Adult cats need regular boosters to maintain protection.

Quarantine of new cats. When introducing a new cat to a household, a quarantine period of at least two weeks in a separate room helps identify cats that may be incubating or shedding FHV-1. This is particularly important when bringing shelter cats into homes with existing cats.

Stress management. Since stress is the primary trigger for viral reactivation, minimizing stressors in your cat’s environment is a practical management strategy. Provide adequate resources in multi-cat households — the general guideline is one litter box per cat plus one extra, multiple food and water stations, and sufficient vertical space and hiding spots. Pheromone products like Feliway may help reduce stress-related behaviors and potentially decrease reactivation frequency.

Environmental hygiene. FHV-1 is easily killed by household bleach diluted 1:32 in water, accelerated hydrogen peroxide, and most commercial disinfectants. Regular cleaning of food bowls, water dishes, bedding, and litter boxes reduces viral load in the environment.

Prognosis and Living with Feline Herpesvirus

The prognosis for cats with FHV-1 depends on the severity and frequency of episodes, the cat’s overall immune health, and whether complications like chronic rhinosinusitis or corneal disease develop.

Most cats with FHV-1 live normal, comfortable lives with occasional mild flare-ups that resolve with or without treatment. These cats may sneeze a bit more when stressed or have intermittent eye discharge, but their quality of life is generally excellent. At the other end of the spectrum, a minority of cats experience frequent, severe recurrences with significant ocular or respiratory complications that require ongoing medical management.

Living with an FHV-1-positive cat means accepting that the virus is a permanent part of their biology and focusing on management rather than cure. Keep a supply of prescribed medications on hand so you can begin treatment at the first sign of a flare-up. Maintain a low-stress, enriching environment. Keep vaccinations current. Monitor the eyes closely and seek veterinary attention promptly if you notice corneal cloudiness, squinting, or discharge that does not improve within a few days.

With attentive care and a good relationship with your veterinarian, most cats with FHV-1 enjoy long, happy lives. The virus is a manageable condition, not a life sentence of suffering.

Frequently Asked Questions

Can feline herpesvirus spread to humans or dogs?

No. Feline herpesvirus type 1 is species-specific and cannot infect humans, dogs, or other non-feline species. Similarly, human herpes simplex virus cannot infect cats. You can safely handle and cuddle a cat with active FHV-1 symptoms without any risk to yourself. However, wash your hands before handling other cats to avoid transferring the virus on your skin or clothing.

Should I adopt a cat that has feline herpesvirus?

Absolutely. Given that up to 90 percent of cats carry FHV-1 in latent form, avoiding herpesvirus-positive cats would mean avoiding most cats. Many shelter cats test positive but live entirely normal lives with infrequent or no clinical episodes. If you have existing cats, they have most likely already been exposed to FHV-1 themselves. The key is ensuring all cats in the household are vaccinated and introducing new cats gradually with a quarantine period.

How often do herpesvirus flare-ups occur?

This varies enormously between individual cats. Some cats experience flare-ups only once or twice in their lifetime, typically during periods of major stress. Others may have episodes every few months. Cats with compromised immune systems or chronic stressors tend to flare more frequently. If your cat is experiencing frequent episodes, work with your veterinarian to identify and address underlying stressors and consider prophylactic antiviral therapy.

Can FHV-1 cause blindness?

In severe cases, yes. Chronic or recurrent herpesvirus keratitis can lead to corneal scarring, corneal sequestration, or symblepharon that impairs vision. However, blindness from FHV-1 is uncommon with appropriate veterinary management. Prompt treatment of ocular flare-ups, avoidance of corticosteroid eye drops (which worsen herpesvirus), and regular monitoring by your veterinarian significantly reduce the risk of serious eye complications.

Is there a cure for feline herpesvirus?

Currently, no. Once a cat is infected with FHV-1, the virus establishes permanent latency in nerve tissue and cannot be eliminated with available medications. Antiviral drugs like famciclovir suppress viral replication during active episodes but do not eradicate the latent virus. Research into gene-editing technologies and novel antiviral approaches is ongoing, but a cure is not yet on the horizon. The focus of management is controlling symptoms, preventing complications, and maintaining quality of life.