Feline Herpesvirus 1



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VIRUSES
HERPESVIRUSES



Pathogenesis

  • Upper respiratory tract infection: Feline Viral Rhinotracheitis
    • Viruses and bacteria are involved in the complex
    • The most frequent aetiologic agent is FHV-1, and less frequently feline calicivirus and/or Chlamydophia psittaci
    • All three agents infect URT respiratory epithelium, although FHV-1 has the highest affinity for this epithelium
      • Feline calicivirus more frequently infects the oral mucosa -> ulcerative stomatitis
      • C.psittaci more frequently infects the conjunctival epithelium -> chronic conjunctivitis
    • Infection of the respiratory epithelium by FHV-1 results in a typical neutrophilic rhinitis with intraepitheial intranuclear eosinophilic inclusion bodies, with expected clinical signs
    • Resolution of clinical signs usually occurs by 7-14 days
    • FHV-1 remains latent in the trigeminal ganglion, and can reactivate at times of stress: Can infect the cornea -> ulcerative keratitis
    • Occasional mortality in kitten or immunocompromised animals usually associated with secondary bacterial infection
  • Erosions can affect the bronchi, resulting in interstitial pneumonia
  • Most common cause of keratitis and corneal ulcers in cat and gummy eyes in kittens
    • Rupture is a particular risk

Epidemiology

  • Widespread
  • Serious infection
  • Latent infection can be reactivated on boarding

Diagnosis

  • Nasal swabs on first week of infection can be cultured for virus isolation

Treatment

For keratitis with corneal ulcers:

  • Subcut omega interferon
  • Topical trifluorothymidine (thymidine analogue) on eyes

Control

  • Killed and live vaccines are available
    • Live vaccines have provoked symptoms in immunosuppressed kittens and are no longer used in the UK