What exactly is feline herpesvirus, and is it the same thing as human herpes?

Feline herpesvirus type 1 (FHV-1) is a species-specific alphaherpesvirus that infects the upper respiratory tract and the surface tissues of the eye; it cannot infect people or dogs, despite sharing a viral family name with human herpes simplex (Cornell Feline Health Center, 2021). The virus targets mucous membranes of the nose, throat, and conjunctiva, where it replicates and damages cells, producing sneezing, congestion, and ocular discharge. Once a cat is infected, the virus travels along sensory nerves to the trigeminal ganglion and establishes a lifelong latent infection, meaning the cat carries the virus permanently even after signs resolve (Merck Veterinary Manual, 2023).

Because the infection is so widespread in the domestic cat population, veterinarians generally treat sudden sneezing and eye discharge in a young cat as a probable FHV-1 case until other causes are ruled out. The AAFP and AAHA feline vaccination guidelines list FHV-1 as one of the core viruses covered by routine kitten vaccination series precisely because exposure is so common in shelters, catteries, and multi-cat homes (American Association of Feline Practitioners, 2020).

What are the first signs owners usually notice?

Early signs typically appear 2 to 5 days after exposure and include paroxysmal sneezing, clear-to-mucoid nasal discharge, watery eyes, and conjunctival redness; some cats also run a mild fever and stop eating because congestion blunts their sense of smell (Cornell Feline Health Center, 2021). Ulcers on the surface of the cornea are a hallmark finding in cats with ocular involvement, and a veterinarian may see a distinctive branching, or dendritic, ulcer pattern on fluorescein staining that is fairly specific to herpesvirus (Merck Veterinary Manual, 2023).

Kittens tend to show more severe disease than adults, sometimes developing ulcerative stomatitis, pneumonia, or, in cats infected in utero or shortly after birth, permanent scarring of the eyelids that fuses them to the eyeball, a condition called symblepharon (Cornell Feline Health Center, 2021). Most otherwise healthy adult cats experience a milder, self-limiting course lasting 7 to 10 days, but the virus is never fully eliminated from the body afterward.

Why does my cat keep getting flare-ups years after the first infection?

Recurrence happens because FHV-1 remains dormant in the trigeminal ganglion for the cat's entire life and reactivates during periods of physiological or psychological stress, including boarding, moving homes, the arrival of a new pet, corticosteroid treatment, or concurrent illness (Cornell Feline Health Center, 2021). During reactivation, the virus travels back down the nerve to the eye or nasal tissue and begins shedding again, which is why a cat can appear healthy for months and then suddenly start sneezing and weeping after a stressful boarding stay.

Roughly 45 percent of infected cats will shed virus intermittently throughout life without ever having obvious clinical signs, acting as silent sources of infection for other cats in the household (Merck Veterinary Manual, 2023). This shedding pattern is a major reason FHV-1 persists so effectively in shelters and multi-cat homes even when no cat currently looks sick.

How do veterinarians confirm it's herpesvirus and not something else?

Diagnosis is often made presumptively from history and clinical signs, since dendritic corneal ulcers seen on fluorescein staining are strongly suggestive of FHV-1, but definitive confirmation requires polymerase chain reaction (PCR) testing of conjunctival or oral swabs (Cornell Feline Health Center, 2021). PCR testing has limitations, however, because vaccinated cats and even healthy latent carriers can test positive without active disease, so veterinarians interpret results alongside clinical findings rather than in isolation.

Veterinarians also work to rule out feline calicivirus and Chlamydia felis, which cause overlapping upper respiratory and eye signs, since a combined respiratory disease panel through a diagnostic laboratory can test for all three pathogens plus Mycoplasma from a single swab (Merck Veterinary Manual, 2023). This differentiation matters for treatment choice, since calicivirus and chlamydial infections respond to different antibiotic and antiviral protocols than FHV-1 does.

What treatments actually help a cat with active herpesvirus signs?

There is no cure that eliminates latent FHV-1 from the nervous system, so treatment focuses on managing active flare-ups and reducing viral load. For cats with corneal ulcers or severe conjunctivitis, veterinarians commonly prescribe topical antivirals such as cidofovir or oral famciclovir, an antiviral medication whose feline dosing protocols have been established through clinical studies at veterinary ophthalmology programs (Cornell Feline Health Center, 2021).

L-lysine supplementation was once widely recommended to suppress viral replication, but a systematic review found no consistent evidence that it reduces clinical signs or shedding, and current guidance from feline medicine specialists has moved away from routine use (American Association of Feline Practitioners, 2020). Supportive care, including nasal saline, gently cleaning discharge from the eyes and nose, and encouraging appetite with warmed, aromatic food, remains a mainstay of home management for uncomplicated cases.

How can I stop the virus from spreading to my other cats?

FHV-1 spreads through direct contact with infected ocular, nasal, or oral secretions and can also survive on shared bowls, bedding, and human hands long enough to transmit between cats, though the virus is fragile and inactivated within about 18 hours outside a host by ordinary cleaning (Cornell Feline Health Center, 2021). Isolating a newly sneezing cat from other household cats, washing hands and changing clothes between handling different cats, and disinfecting shared surfaces with a diluted bleach solution or another disinfectant effective against herpesviruses all reduce transmission risk.

Vaccination does not prevent infection outright but significantly reduces the severity of clinical disease and is considered a core vaccine for all cats by veterinary vaccination guidelines, typically given as a kitten series followed by regular boosters (American Association of Feline Practitioners, 2020). Shelters and catteries, where crowding and stress are highest, see the greatest benefit from strict hygiene protocols combined with vaccination because both viral shedding and susceptibility are amplified in group housing.

What does long-term management look like for a cat with recurring flare-ups?

Most cats with FHV-1 settle into a pattern of occasional, mild recurrences tied to identifiable stressors, and many owners learn to recognize the earliest sneeze or eye squint as a cue to start supportive care before signs worsen. Reducing environmental stress through consistent routines, adequate hiding and resting spaces, and feline pheromone diffusers can lower the frequency of reactivation episodes, since stress hormones are a documented trigger for viral shedding (Cornell Feline Health Center, 2021).

Cats with a history of chronic or severe ocular involvement may need periodic rechecks with a veterinary ophthalmologist to monitor for corneal scarring, chronic keratitis, or the sequestrum formation that can occur after repeated corneal damage (Merck Veterinary Manual, 2023). With appropriate management, the large majority of affected cats live full, comfortable lives, and the condition is generally viewed as a manageable chronic nuisance rather than a life-limiting disease.