Cat flu is a general name given to infectious acute feline respiratory disease caused by a number of organisms. It is commonly seen in cats that have not been vaccinated, especially when they are kept in an over-crowded, dusty environment with poor ventilation and high humidity. A huge majority (almost 80%) of the infections are caused either by feline calicivirus (FCV) or feline rhinotracheitis virus (FRV or herpes virus). The rest are caused by organisms known as feline coronavirus, Bordetella bronchiseptica, Pasturella multocida, Mycoplasma (parasitic bacteria) or Chlamydophila felis. Many cases of cat flu are tested positive for infection by more than one of these infectious agents.
Cat flu is a contagious disease, and even cats without visible signs of the infection may pass it on to a healthy cat. The symptoms of cat flu include:
- Watery eyes.
- Conjunctivitis, the inflammation of the mucous membrane that covers the eyeball.
- Nasal discharge that is initially serous but later comprises of mucous and pus.
- Tongue and mouth ulcerations.
- Increased secretion of saliva.
- Appetite loss.
- Limping syndrome, seen mostly in infection by the feline calicivirus.
Diagnosis is usually presumptive, based on the visible symptoms and history of exposure. While different virus strains produce identifiable characteristic symptoms, in a mixed infection, it is difficult to determine the infectious agent from clinical signs only.
Symptoms of FRV tend to be severe and prominently seen as conjunctivitis, copious nasal discharge and coughing. FCV, on the other hand, is associated with milder symptoms and ulcerations in the mouth. Bordetella bronchiseptica is primarily associated with a hacking cough and commonly seen in cats with a recent history of living in crowded conditions.
While these are related to acute conditions, chronic feline upper respiratory infections are defined as chronic post-viral rhinitis and affect the sinuses, the air filled cavities in the bones of the skull. The viral infection causes damage to the mucosa in the nasal passage, which leads to secondary bacterial infections. As the disease at this stage does not allow identification of either FCV or FRV infection, it is thus also termed as idiopathic chronic rhinitis. Occasional cases of unusual mycobacterial infection leading to chronic rhinitis have also been reported.
To control feline respiratory diseases you should ensure that your cat has undergone a vaccination program before being exposed to crowded situations. Vaccinations may not prove to be a sure shot protection, but they can reduce the symptoms of cat flu to a great extent. Other preventive measures include good ventilation and proper hygiene. Kittens are more susceptible to respiratory infections and should be weaned in isolation.