Feline Herpes Virus (FHV-1), also called Feline Viral Rhinotracheitis, is one of the most common causes of Upper Respiratory Infections (URI) in cats. Most cats that become infected with FHV-1 will have a chronic or latent infection, meaning that the DNA of the virus remains in the body even after the appearance of illness is gone. Most of these cats will recover and appear healthy, but some may have a relapse in times of stress (new home or new pet in the home, moving, boarding, injury or illness). A few will continue to have mild signs of illness most or all of the time.

Signs of FHV-1 infection in cats include discharge from or irritation of the eyes, sneezing, nasal discharge, and nasal congestion. Systemic signs can include fever and loss of appetite or energy level.

Testing is usually not performed to diagnose the exact cause of URI in cats, as symptoms are usually mild. In outbreaks or unusual cases, PCR testing is available for common viral and bacterial causes of URI.

FHV-1 is included in FVRCP (“feline distemper”) vaccines, which are recommended for all cats healthy enough to receive routine vaccinations.

Treatment is not always required for FHV-1 infections, as the immune system of an otherwise healthy cat will usually respond without any medication. Antibiotics are often prescribed for associated bacterial or mycoplasma infections. For more severe cases, there are antiviral oral and eye medications available for cats with FHV-1. No benefit has been shown for administration of lysine supplements, especially if the cat must be forced to take the supplement, rather than eating it voluntarily in food or treats.

Signs of an FHV-1 flare-up can include watery discharge from the eyes or nose, sounds of nasal congestion, frequent sneezing, or loss of appetite. If you notice these signs, you should consult your regular veterinarian to determine whether any treatment is required.

FHV-1 can be spread by direct contact, shared bowls or toys, or through the air by sneezing or coughing. It can also be spread on hands and clothes when people handle multiple cats or their belongings. Cats are generally contagious only when showing active signs of the infection – cats with chronic or latent infections that appear healthy are not producing copies of the virus that can spread to other cats. Healthy adult vaccinated cats should be protected against FHV-1 infection, but care should be taken not to expose a sick cat to kittens under 4 months, or to unvaccinated, elderly or sick cats.