Feline Herpesvirus-1 (FHV-1) in Kittens and Cats

Oftentimes, discussions surrounding infectious diseases swirl around the safety of the vaccines against them. Indeed, those are important discussions. However, factors such as:

  • viral zoonoses;
  • speed of viral transmission;
  • viral spread;
  • viral hardiness;
  • onset and characteristics of symptoms;
  • viral shedding period;
  • severity of the disease; and,
  • residual effects from infection

versus the vaccine itself are often overlooked. Viruses affecting cats provide good examples of these factors when making assessments of disease status versus vaccine. One such example is feline herpesvirus-1 (FHV-1), which is also known as feline viral rhinotracheitis.

Zoonoses of FHV-1

FHV-1 is species-specific and can only infect domestic and wild cats.

Quickness of FHV-1 Transmission

It takes less than 24 hours for a newly infected cat to spread the disease to other cats.

Spread of FHV-1

FHV-1 is spread when a cat encounters virus particles that are shed through saliva, eyes, and nose of an infected cat. While cat-to-cat transmission can occur, clothing, furniture, and bowls can also be contaminated.

Hardiness of FHV-1

Hardiness refers to how long the virus can live outside the body in the environment.

Regarding FHV-1, the virus particles can be active for approximately 30 minutes. Objects can be a source of infection for up to 18 hours if they are moist or wet. Once the surfaces are dry, the virus loses and dies within a short period of time.

Onset and Characteristics of FHV-1

FHV-1 incubates for approximately two to five days before the signs of symptoms. Remember, that newly infected cats are actively shedding the virus within 24 hours.

Characteristics of FHV-1 appear as a “cold” or “allergies” such sneezing, nasal congestion, blinking and squinting. Possibly the most telltale signs are clear, yellow, or green pus emanating from the eyes or nose.

Cats may also exhibit fatigue, poor appetite, and enlarged lymph nodes.

One of the troubling aspects of FHV-1 is that it is difficult to distinguish from feline calicivirus.

Period of FHV-1 Shedding

As mentioned previously, cats can start shedding the virus in less than 24 hours. However, the cat can continue to shed the virus for up to twenty days.

Severity of FHV-1

If a companion pet parent catches the symptoms early enough, the cat should recover within a couple of weeks when given adequate care under the advisement of a veterinarian.

Death may be a result with severe disease, particularly in unvaccinated, young, and immunosuppressed cats.

Kittens could have damage to the bones of their faces, which can suppress the immune system resulting in recurring nasal and eye conditions.

Residual Effects from FHV-1 Infection

Similar to genital herpes in humans, FHV-1 will always be with the cat in a dormant state and can be reactivated. Additionally, any cat that has been infected with FHV-1 may always be infectious to other cats.

Handling Active Infections

All companion pet parents who notice any signs or symptoms should isolate the cat immediately from other cats and call their veterinarian.

All surfaces should be immediately disinfected. Soak all objects in a bleach and water solution for at least five minutes. If an item cannot be bleached, thoroughly washing in hot water and soap would be the next resort. Soft toys and blankets should be washed in hot water and laundry detergent. You may also want to use a furniture cleaner for upholstered furniture. Remember, the virus only survives on wet or moist surfaces, so companion pet parents may want to block access to these items from non-symptomatic cats for a day or two.

Vaccination Against FHV-1

The vaccine against FHV-1 does not produce sterilizing immunity. While non-sterile immunity may not protect the animal from infection, it should keep the infection from progressing to severe clinical disease.

Dr. Jean Dodds does recommend vaccinating against FHV-1.

Her protocol is to give the combination vaccination of panleukopenia (feline parvovirus), calicivirus, feline viral rhinotracheitis (feline herpesvirus-1) between 8-9 weeks of age and boostered at 12-13 weeks of age. As well, she specifies an additional booster of this combination at 1 year of age. This vaccine is written as FVRCP.

After that, it is best to revaccinate every one to three years with the intranasal combination of FHV-1 and feline calicivirus (FCV). Even though the vaccine against FHV-1 lasts 4-5 years based upon published challenge trials, pharmaceutical companies do not make a standalone vaccine against FHV-1.

Should cats with lifelong FHV-1 due to infection receive the vaccine?

Yes; because it will tamp down disease severity if reactivation occurs.

What about an antibody titer test to find out if my companion cat needs the vaccine?

The antibody titer test is not a reliable gauge to find out if a cat has immunity against FHV-1. FHV-1 necessitates both an antibody and cell-mediated response for effective immunity.


2020 AAHA/AAFP Feline Vaccination Guidelines, American Animal Hospital Association, 2020, https://www.aaha.org/aaha-guidelines/2020-aahaaafp-feline-vaccination-guidelines/feline-vaccination-home/.

Dodds, W. Jean. “Feline Vaccination Protocol.” Hemopet, https://hemopet.org/feline-vaccination-protocol-by-dr-jean-dodds/.

Dodds, W. Jean. Dodds Reviews the 2020 AAHA/AAFP Feline Vaccination Guidelines, Hemopet, 21 Sept. 2020, https://hemopet.org/dodds-reviews-the-2020-aaha-aafp-feline-vaccination-guidelines/.

Maes, Roger. “Felid herpesvirus type 1 infection in cats: a natural host model for alphaherpesvirus pathogenesis.” ISRN veterinary science vol. 2012 495830. 14 Nov. 2012, doi:10.5402/2012/495830, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671728/.

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