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 is generally present in animals over 1 year of age. 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