FELINE VIRAL RHINOTRACHEITIS

Nature of the disease
Feline viral rhinotracheitis (FVR) is an infectious respiratory disease of cats characterised by fever, conjunctivitis, nasal and ocular discharges and sneezing. 

It is caused by a herpesvirus (feline herpesvirus 1) which is the most common agent found in the feline respiratory disease complex which also commonly includes feline calicivirus, chlamydiosis and mycoplasmasosis.

Classification
SPC List D disease
Susceptible species
Cats. Young cats are more susceptible and clinical disease is more severe in kittens and old cats. Some breeds e.g. Siamese and Burmese are more severely affected.
Distribution
Feline herpesvirus 1 is widely distributed in cat populations around the world.
Clinical signs 
Clinical signs are usually more apparent in younger cats. There is:
  • Fever
  • Depression and anorexia
  • Sneezing
  • Ocular and nasal discharges
  • Acute conjunctivitis may be a feature and lead to ulcerative keratitis. 
  • Tongue ulceration and pneumonia may also occur. 
  • Pregnant cats may abort.

Secondary bacterial infections are common. Mortality is low, except in kittens (especially Siamese kittens) and old cats.

Post-mortem findings 
  • Conjunctiva red and oedematous,
  • Mucopurulent inflammation of the eye and nose — thick yellow discharge· necrotic ulceration of the nose and occasionally the oral mucosa,
  • Turbinate bones may be necrotic and sinuses inflamed

In kittens death is usually due to bronchopneumonia associated with secondary bacterial infections.

Differential diagnosis 
Other important cause of respiratory disease in cats include:
  • Feline calicivirus
  • Feline pneumonitis
  • Chlamydia infection
  • Mycoplasma infection
  • Allergic Rhinotracheitis
Specimens required for diagnosis 
Swabs from the pharynx, eye, nose or ulcers should be collected for virus isolation.
Impression smears from conjunctiva and tongue ulcers for histology (to demonstrate intra nuclear inclusion bodies).
Blood samples for serology. These should be taken at the start of disease and 2 weeks later to show antibody development.
Transmission   
FVR is acquired through inhalation of aerosols. The virus is spread through coughing and sneezing by infected cats. Droplets may spread the infection up to a metre, so close contact between infected and susceptible cats is generally necessary.
Ten per cent of recovered cats become asymptomatic carriers. Stress exacerbates shedding of virus by carriers.
Risk of introduction   
FRT is most likely to be introduced through importation of infected cats or infected material such as cage. 

N.B. Recovered cats can become asymptomatic carriers.

Control / vaccines  
Good supportive therapy will aid recovery and reduce mortalities. This includes:
  • Sponging away exudates around eyes and nostrils
  • Maintaining patency of airways and improving airflow with steam vaporisers and inhalation decongestants
  • Intravenous fluids for treating any dehydration
  • Antibiotics to control secondary bacterial infections
  • Stimulating appetite with strong smelling foods (e.g. sardines)

Two modified live vaccines are available and combine feline rhinotracheitis and feline calicivirus valence. Inactivated vaccine are also available.

References
  • Coryza Contagieux du chat, In Dictionnaire Pratique de Thérapeutique Canine et Féline, Masson, Forth ed, 1997, Paris, p 146-147
  • Feline Respiratory Disease Complex, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p 1115-1117