Feline Calicivirus

Introduction

The normal hosts for this virus are domestic cats and cheetahs. The virus has a high morbidity/low mortality rate, but affected animals can be further compromised by concurrent infection. The incubation period is 2-10 days.

Clinical signs include:

• Vesicles and ulcers of the oral epithelium (2-5mm)
• Nasal and ocular discharge
• Sneezing
• Anorexia

Variable signs include:

• Pyrexia
• Dyspnoea
• Conjunctivitis
• Rhinitis
• Tracheitis
• Pneumonia

Differential Diagnoses may include:

• Feline Herpes
• Clamydophila felis
• Bordetella bronchiseptica

Recovery can be followed by carrier status

Epidemiology

• FCV is endemic worldwide
• Transmission occurs through direct contact with secretions of carrier cats or indirect contact via drinking bowls, etc
• Clinical disease is most frequently seen in kittens
• Active immunity formed by 1 year of age
• Transmission occurs from diseased and recovered (carrier) animals
• Antigenic variation means that subclinical reinfections can occur

Antigenicity

• Single serotype with antigenic variation

Strains

Recent strains have been shown to cause systemic disease:

• Initial upper respiratory signs are followed by:
  • Severe pyrexia
  • Oedema, particularly of the head and limbs
  • Skin ulcers
  • Icterus and Petchiae
• Mortality of up to 50%, and higher in cats over 1 year of age
• Conventional vaccination ineffective

Diagnosis

• Clinical signs unhelpful due to differentials
• Nasal, conjunctival, or oropharyngeal swabs taken for virus isolation
  • Diagnosed by pyknosis (Feline herpes causes cellular swelling and syncitia)

Control

Virulent isolate outbreak:

• Quarantine and restrict movement

Prevention:

• Vaccination:
  • Live or dead vaccines available
  • Contain broadly cross-reactive strains
  • In combination with feline herpes and panleukopenia virus
  • Live nose-drop vaccine now available in US
  • Particular concern for catteries

• Rhinitis,
• Suggested in the presence of ulceration of the dorsal and lateral edges of the tongue, hard palate and external nares
• Lesions present may include interstitial pneumonia with necrotising bronchiolitis
• Also see Feline viral rhinotracheitis above