What Is Feline Herpesvirus?
Feline herpesvirus is a common viral infection that affects the upper respiratory tract, eyes, and mouth of cats. It's one of the primary causes of feline rhinotracheitis (inflammation of the nose and windpipe) and is closely related to human herpes viruses in that it establishes lifelong latency—meaning your cat can carry the virus indefinitely, even when showing no symptoms. During dormant periods, infected cats shed the virus intermittently and can pass it to other cats without appearing sick.
- ✓FHV-1 is a DNA virus that attacks mucous membranes
- ✓Causes inflammation of the upper respiratory system
- ✓Can also lead to corneal ulcers and conjunctivitis
- ✓Most severe in kittens, elderly, or immunocompromised cats
Recognizing Symptoms and Signs
Symptoms of feline herpes typically appear 2–10 days after exposure and can range from mild to severe depending on your cat's age, overall health, and stress levels. Classic signs include sneezing, nasal discharge (often clear at first, then yellowish), watery or goopy eyes, and lethargy. Some cats develop mouth ulcers, drool excessively, or lose their appetite, while others may run a fever or show conjunctivitis (pink, inflamed eye tissue).
- ✓Sneezing and nasal congestion—sometimes prolonged
- ✓Clear to colored nasal and eye discharge
- ✓Ulcers on the tongue, gums, or lips
- ✓Squinting, tearing, or light sensitivity from eye involvement
- ✓Loss of appetite due to mouth pain or blocked nose
- ✓Lethargy and reduced activity during acute infection
How Herpes Spreads and Risk Factors
Feline herpes spreads through direct contact with infected saliva, nasal secretions, or eye discharge—typically via nose-to-nose contact, shared food bowls, or grooming. An infected cat may shed the virus continuously or intermittently throughout its lifetime, making multi-cat households particularly vulnerable. Stress, illness, poor nutrition, overcrowding, and environmental changes are common triggers that reactivate dormant virus and cause flare-ups in previously infected cats.
- ✓Spreads through respiratory droplets and saliva
- ✓Cats can shed virus even when asymptomatic
- ✓Stress, temperature changes, and illness trigger reactivation
- ✓Kittens and senior cats face higher severity risk
- ✓Immunocompromised cats (FIV, FeLV positive) are especially vulnerable
- ✓Multiple cats in one home increase transmission risk
Diagnosis and When to See Your Vet
Your veterinarian diagnoses feline herpes primarily through clinical signs and physical examination, though they may perform a nasal or conjunctival swab for PCR (polymerase chain reaction) testing to confirm the virus. There is no blood test to determine if a cat carries latent herpes, so diagnosis is based on symptoms when they occur. If your cat shows persistent sneezing, nasal discharge, eye problems, or mouth ulcers lasting more than a few days, a vet visit is important to rule out other conditions and begin supportive care.
- ✓Diagnosis is usually clinical based on symptoms
- ✓PCR swabs can confirm FHV-1 infection
- ✓No cure; treatment is supportive and symptom-focused
- ✓Eye exams can reveal corneal ulcers
- ✓Bloodwork may check for secondary bacterial infection
Treatment and Home Care
There is no cure for feline herpes, but most cases resolve with supportive care and time as your cat's immune system controls the infection. Treatment focuses on keeping your cat comfortable, maintaining nutrition, managing eye and respiratory symptoms, and preventing secondary bacterial infections. L-lysine, an amino acid supplement, is commonly used to help reduce the frequency and severity of flare-ups, though evidence is mixed—discuss its use with your vet before starting. Severe cases with corneal involvement may require antiviral eye drops (like idoxuridine) prescribed by your veterinarian.
- ✓Keep your cat hydrated and eating (warm wet food may help)
- ✓Use a humidifier to ease respiratory congestion
- ✓Gently clean eyes and nose with warm, damp cloth
- ✓L-lysine supplements may help reduce flare-up frequency
- ✓Antibiotics only if secondary bacterial infection develops
- ✓Rest and stress reduction are key to recovery
Prevention and Long-Term Management
While you cannot prevent a cat from catching herpes if exposed, you can reduce flare-ups and spread by minimizing stress, maintaining good nutrition, keeping the environment clean, and isolating infected cats from others during outbreaks. The feline herpes vaccine (FVRCP) is included in core kitten vaccinations and helps reduce severity of infection but does not prevent it entirely. For cats with recurrent flare-ups, consistent L-lysine supplementation, environmental control (low stress, clean living space), and prompt veterinary care during symptoms are essential.
- ✓Vaccination (FVRCP) reduces severity but doesn't prevent infection
- ✓Minimize stress through routine, safe spaces, and enrichment
- ✓Separate newly infected cats to prevent spread
- ✓Feed high-quality diet to support immune function
- ✓Keep litter boxes, food, and water areas scrupulously clean
- ✓Monitor for flare-ups and contact vet at first signs
