Felis ISSN 2398-2950

Feline herpes virus: feline rhinotracheitis virus

Synonym(s): FHV-1, feline rhinotracheitis virus, cat flu, FVR

Contributor(s): Susan Dawson, Melissa Kennedy




  • Family: Herpesviridae.
  • Subfamily: Alphaherpesvirinae.

Active Forms

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Clinical Effects



  • Route of infection: intranasal, oral or conjunctival.
  • Virus is shed in oronasal secretions from 24 hours post-infection and persists 1-3 weeks.
  • Transmitted by direct contact and by short-distance aerosolization through sneezing.
  • Indirect via contaminated food bowls, hands, etc (less important than direct transmission due to virus susceptibility to dessication, disinfectants, etc).
  • Fomite transmission is more important than aerosol in cats due to small lung tidal volume.

Pathological effects

  • Neutralizing antibody recognizes gp60, the viral hemagglutinin, which is essential for attachment to cells.
  • Neutralizing titers are low: 1:16-1:64.
  • Neutralizing antibodies appear 20-30 days post-infection.
  • Infection is lifelong and latently infected cats may still have neutralizing antibodies.
  • Maternally derived antibody may last until 6-10 weeks of age.
  • FHV-2 serologically distinct from FHV-1.
  • Antibodies detected by immunofluorescence may decrease to low or undetectable levels within several months.
  • Virus growth occurs in the epithelium of the nasal mucosa, conjunctiva, tonsil and nasal turbinates: tissue damage is due to viral cytolysis. Clinical signs of upper respiratory tract disease due to this damage. May see severe nasal and/or ocular discharge, sneezing, anorexia, depression.
  • Corneal lesions seen on days 3 and 12 of primary infection, in kittens: corneal edema Eye: corneal opacity, ulceration Ulcerative keratitis and rupture of eyeball often around 2-4 weeks of age. In older kittens and cats: dendritic keratitis, adhesions to conjunctivae or to iris.
  • May leave surviving cats with chronic ocular discharge , chronic sinusitis Sinusitis or rhinitis Rhinitis.

Other Host Effects

  • All infected cats become latently infected as carriers.
    Kittens may become latent carriers without ever showing signs.


Control via chemotherapies

  • For ulcerative keratitis: 0.1% ophthalmic solution of 5-iododeoxyuridine 4-6 times daily for 3-5 days (Acyclovir Acyclovir, used for herpes simplex in man, less active against FHV).
  • Interferon useful for ocular disease - L-lysine tablets twice daily (endogenous interferon inducer).
  • Broad spectrum antibiotic cover useful against secondary bacterial infection.
  • Good nursing, especially to encourage feeding, as cats will not eat what they cannot smell (use strong-smelling foods like sardines).
  • Eucalyptus oil on bedding or bandanna, or steam inhalation, to aid clearing of nasal passages.

Control via environment

  • Disinfectant: Most detergents or bleach diluted 1:32 in water with washing-up liquid.


  • Attenuated living and inactivated systemic vaccines available.
  • Inactivated vaccine

Other countermeasures

  • FHV prevention in kittens:
    • Boost queen's immunity before conception.
    • Isolate queen from other cats before birth of kittens.
    • Ensure good intake of colostrum to supply maternally derived immunity.
    • Wean kittens early, at 2-3 weeks of age, and keep isolated from all other cats.
    • Vaccinate at 8 and 12 weeks of age.
    • In some kittens early vaccination is used, but is not licensed in UK.


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Further Reading


Refereed papers

  • Recent references from VetMedResource and PubMed.
  • Dawson S, Willoughby K, Gaskell R M et al (2001) A field trail to assess the effect of vaccination against feline herpesvirus, feline calicivirus and feline panleucopenia virus in 6-week old kittens. JFMS 3, 17-22.
  • Binns S H, Dawson S, Speakman A J, Cuevas L E et al (2000) A study of feline upper respiratory tract disease with reference to prevalence and risk factors for infection with feline calicivirus and feline herpesvirus. J Feline Med and Surg 2, 123-133.
  • Dawson S & Willoughby K (1999) Feline infectious upper respiratory tract disease - an update. In Practice 5, 232-252.
  • Dawson S, Gaskell R & Jarrett O S (1999) Vaccination in cats - an update. In Practice 21, 71-74.
  • Sykes J E, Browning G F, Anderson G, Studdert V P & Smith H V (1997) Differential sensitivity of culture and the polymerase chain reaction for detection of feline herpesvirus 1 in vaccinated and unvaccinated cats. Arch Virol 142, 65-74.

Other sources of information

  • Nasisse M P & Weighler B J (1997) The diagnosis of ocular feline herpesvirus infection. Vet Comp Opthal 7(1), 44-51.
  • Gaskell R M & Bennett M (1996) Feline Infectious Respiratory Disease. In: Feline and Canine Infectious diseases. Oxford: Blackwell Science, pp 3-28. ISBN: 0 6320 3446 7.
  • Gaskell R M, Dawson S (1994) Viral-induced upper respiratory tract disease. In: Feline Medicine and Therapeutics. Eds: Chandler E A, Gaskell C J & Gaskell R M. Oxford: Blackwell Science, pp 453-472. ISBN: 0 6320 4133 1.