Feline Herpesvirus (FHV-1) in Cats

Feline herpesvirus (FHV-1) is a common viral infection in cats that can cause respiratory and eye symptoms, including sneezing and nasal discharge. 

More than 90% of cats are exposed to feline herpes at some point in their lives, and symptoms are usually self-limiting and resolve after a couple of weeks.

What Is Feline Herpesvirus (FHV-1)?

Feline herpesvirus (FHV-1) is a virus that affects a cat's upper respiratory tract and the structures of the eye. It spreads between cats through direct contact with infected oral, nasal, or eye secretions.

Within 24 hours, a newly infected cat can transmit feline herpesvirus to other cats, so it's important to seek veterinary care immediately.

Feline herpesvirus is the most common viral cause of sneezing and nasal discharge in cats. Changes to the structures of the eye are also associated with feline herpes infection.

Young cats are most affected, although feline herpesvirus can occur at any age. Cats at increased risk include those in multi-cat households, shelters, rescues, and catteries.

Outdoor and community cats may also become infected through contact with affected cats.

What Are the Symptoms of Feline Herpesvirus in Cats?

Symptoms of feline herpesvirus in cats can vary in severity and commonly include upper respiratory signs such as sneezing and nasal discharge, as well as eye symptoms such as discharge and conjunctivitis.

Upper respiratory symptoms may include:

• Sneezing
• Nasal discharge
• Fever
• Loss of appetite
• Coughing

Eye symptoms may include:

• Eye discharge
• Conjunctivitis (pink eye) or chemosis (enlargement of the pink lining of the eye)
• Changes in the color of the eye
• Corneal ulcers (scratches or tears of the clear part of the eye)

In severe cases, changes to the skin around the face may include:

• Redness
• Swelling
• Crusting
• Hair loss

How Does Feline Herpesvirus Spread?

Feline herpesvirus is highly contagious and spreads from cat to cat through secretions or close direct contact.

Cats in shelters, breeding catteries, and pet stores can readily spread the virus when they sneeze. The virus can also be present on the hands or clothing of people who care for infected cats.

Feline herpesvirus attacks the lining of the nose, tonsils, conjunctiva (lining of the eye), and cornea (visible part of the eyeball). As the virus continues to make copies of itself, it may spread through secretions or close direct contact.

If not treated early, the virus can infiltrate the bones associated with the nose and mouth, causing long-term physical damage.

How Is Feline Herpesvirus Diagnosed?

Feline herpesvirus is diagnosed based on a cat's physical exam, symptoms, and history, along with PCR testing.

PCR testing: Veterinarians may perform a PCR test using swabs from deep in the mouth or the eye, or biopsies from the skin.

However, a PCR test does not differentiate between an active infection and a chronic carrier state.

A positive PCR result may mean:

• The cat was infected by another sick cat and is now a carrier of the virus.
• The cat has been vaccinated for feline herpes.
• The cat is showing signs of an active feline herpes infection.

Because of this limitation, diagnosis is usually based on the PCR results along with a physical exam, the cat's symptoms, and their history.

How Is Feline Herpesvirus Treated?

Treatment for feline herpesvirus depends on the severity of the disease, as well as a cat's vaccination status, age, and underlying health conditions. Supportive care is the foundation of treatment.

Supportive Care

Supportive care is aimed at decreasing more severe symptoms, such as pneumonia and physical damage to the nose and eye structures.

Supportive care may include:

• Fluids for hydration
• Routine cleaning of the nostrils and eyes, if affected

The virus is typically active for seven to 10 days. In mild cases, cats may require no treatment as symptoms improve. In severe cases, a cat may need to be stabilized in the hospital before supportive care can continue at home.

Antiviral Treatment

Currently, there are no specific medications for the herpes virus in cats. However, in severe cases, human antiviral medications such as famciclovir may help.

Famciclovir may reduce clinical signs and decrease virus shedding in the secretions of infected cats.

Eye Treatment

For cats with eye symptoms, topical eye medications such as Terramycin ointment or tobramycin drops may be used to treat secondary bacterial eye infections.

Supplements and Probiotics

Lysine immune supplements decrease the virus's ability to replicate and are available as a powder, paste, or treat.

Probiotics containing Enterococcus faecium support the immune system.

Treating Secondary Bacterial Infections

Antibiotics work against bacteria, so they are not used in every case of feline herpesvirus.

If a secondary bacterial infection is present, antibiotics may be used to treat the infection while the virus runs its course. Clavamox or azithromycin may be prescribed for secondary bacterial upper respiratory infections.

What Is the Prognosis for Cats With Feline Herpesvirus?

When feline herpesvirus is caught early, most cats with symptoms recover within 10–14 days with supportive care.

Severe disease can result in death, especially in kittens and cats that are immunosuppressed.

In severe cases, or when cats are affected at a very young age, physical damage to the bony structures of the face can occur, causing deformities and scarring.

This damage can predispose affected cats to complications such as pneumonia, chronic nasal disease, and recurrent flares of infection.

How To Prevent Feline Herpesvirus

You can help prevent feline herpesvirus by isolating sick cats, cleaning shared spaces and items, reducing stress, and vaccinating your cat.

• Isolate sick cats. Separate cats showing signs of upper respiratory disease or abnormal eye discharge from other cats.
  • Give the affected cat an individual water bowl, food bowl, litter box, toys, and bedding.

• Clean shared spaces and items. FHV-1 is very susceptible to disinfectants. The feline herpesvirus survives only 18 hours outside of the host and is easily inactivated by bleach.
• Reduce stressors. Give cats housed together enough space to eat, drink, and use a litter box without crowding or aggression. Maintain a normal routine of deworming, enrichment, and rest. Pheromone therapy, such as Feliway, can also reduce stress for cats.

• Vaccinate your cat. A vaccine can decrease the symptoms associated with feline herpesvirus infection. This combination vaccine protects against feline herpes, feline calicivirus, and feline panleukopenia (feline distemper).

Vaccinated cats can still become infected with feline herpesvirus and become chronic carriers. However, vaccinated cats develop milder symptoms and shed less virus for a shorter period of time compared with unvaccinated cats.