Feline Herpesvirus (FHV-1): Managing Chronic Respiratory and Eye Disease in Cats

Feline herpesvirus type 1 is one of the most common infectious agents in cats worldwide, causing recurrent respiratory and eye disease throughout life. Understanding its management is essential for the welfare of the millions of cats who carry this virus.

Key Facts

Feline herpesvirus type 1 (FHV-1, also called feline rhinotracheitis virus) is a highly contagious alpha-herpesvirus that causes upper respiratory disease and ocular disease in cats
After initial infection — typically in kittenhood through contact with infected cats — FHV-1 establishes lifelong latency in sensory nerve ganglia; the virus cannot be eliminated from the body
Reactivation of latent virus can be triggered by any stressor: rehoming, new animals in the household, illness, surgery, corticosteroid treatment, or even seasonal changes
During active infection, cats show sneezing, nasal discharge, conjunctivitis, and sometimes corneal ulcers; severe cases cause bronchopneumonia, particularly in kittens and immunocompromised adults
Corneal disease is a particular welfare concern: FHV-1 can cause dendritic and stromal ulcers, corneal sequestrum (black pigment deposits requiring surgical removal), and ultimately corneal scarring and reduced vision
Vaccination with modified-live or inactivated FHV-1 vaccines does not prevent infection but significantly reduces the severity of clinical disease and shedding
L-lysine supplementation was historically recommended to reduce viral replication but evidence of efficacy in cats is poor and current guidelines do not support its routine use
Antiviral treatment with famciclovir (oral) or cidofovir (topical) can reduce severity and duration of active FHV-1 episodes, particularly ocular disease

Welfare Considerations

FHV-1 creates a lifelong welfare management challenge. Cats with active disease experience genuine discomfort: the combination of nasal congestion (reducing the ability to smell and therefore interest in food), conjunctivitis (causing eye pain and discharge), and sneezing represents a cluster of uncomfortable symptoms that recur throughout life whenever the cat is stressed. The inevitability of recurrence means that welfare-conscious management requires identifying and minimising stress triggers — a task that requires good understanding of feline stress physiology and the specific stressors affecting each individual cat. Multi-cat households present particular challenges because inter-cat conflict is both a trigger for FHV-1 reactivation and a consequence of the lethargy and irritability that active disease causes. The ocular complications of FHV-1 can cause lasting welfare compromise: corneal ulceration is painful, and recurrent episodes can progressively damage vision in ways that affect the cat's ability to navigate, hunt, play, and generally engage with its environment. Active management of ocular disease with appropriate antivirals and analgesics is therefore a meaningful welfare investment.

What You Can Do

Vaccinate all cats with appropriate core vaccines including FHV-1; while vaccination does not prevent infection, it significantly reduces clinical severity
Minimise stress triggers for FHV-1-positive cats: maintain stable household routines, provide adequate resources in multi-cat households, and use pheromone diffusers during unavoidable stressful events
Seek veterinary assessment promptly for any cat showing corneal cloudiness, squinting, or eye discharge — FHV-1 corneal ulcers require appropriate antiviral treatment to prevent scarring
Consider famciclovir treatment for cats with frequent or severe FHV-1 flares — antiviral therapy reduces duration and severity of episodes and is particularly valuable for ocular disease management
Discuss with your vet whether immunomodulating supplements (such as omega-3 fatty acids) or targeted nutritional support may help maintain immune resilience in cats with frequent reactivation
If adopting from a rescue setting, be aware that the stress of rehoming commonly triggers FHV-1 reactivation — plan to provide a quiet, low-stress environment during the adjustment period