Cats are susceptible to a range of infectious diseases, some of which can be protected against using vaccinations. Routine care including vaccinations have improved the welfare of cats and helped to prevent serious and sometimes life-threatening illness. Cat flu is an infectious disease-causing upper respiratory infections and a range of other troublesome symptoms. 

Cats who are suffering with “cat flu” (which is NOT an influenza virus, by the way) may sneeze, have sore runny eyes or a temperature amongst other signs. The main causes of cat flu are two viruses, feline herpes virus and feline calicivirus. Certain types of bacteria can also cause cat flu, but viral infection is the more often the culprit.

Feline calicivirus and feline herpes virus are common, highly contagious and easily spread.  

The viruses are readily transmitted between cats by:

  • Contact with a contaminated environment (for example bedding), this is more of a concern with calicivirus which can persist longer in the environment.
  • Shared litter trays or food bowls.
  • Inhaling sneeze droplets from an infected cat.
  • Direct contact, through contact with saliva, or nasal and ocular secretions.

Cat flu can cause a range of symptoms

These can range from mild to very serious, particularly for young or elderly cats. The most common symptoms seen include:

  • Acute upper respiratory tract infection is the most common presentation seen with cat flu. Signs may include; lethargy, high temperature, sneezing, conjunctivitis, discharge from the nose or eyes, loss of appetite, and coughing. 
  • Inflammation of the gums or mouth.
  • Painful joints might be seen at the time of upper respiratory signs in some young cats.
  • Kittens with cat flu may develop more severe symptoms including pneumonia and very sore eyes, occasionally leading to the loss of the eye.
  • Cats who contract feline herpes virus cats can become lately infected, meaning they are lifelong carriers of the infection. The virus might continue to be shed or shed intermittently in times of stress. In some cases, the shedding of the virus might lead to a reoccurrence of mild symptoms in some cats. 

The good news is that there are vaccinations which can protect against the most common causes of cat flu. 

Vaccinations work by administering an inactivated portion of the virus to the cat. This shows the immune system the disease without actually causing the illness. The cat is then able to mount an immune defence including producing antibodies and activating infection-fighting T-cells. If the vaccinated cat later encounters the virus it is then able to fight off the infection. Unvaccinated cats who have never encountered the virus previously are likely to become unwell as their immune system hasn’t been primed ready to ward off the virus. 

Core vaccines

The World Small Animal Veterinary Association provide guidelines on the vaccination protocols for cats and dogs which are applicable worldwide. The WSAVA considers the vaccinations against feline calicivirus and feline herpes virus as core recommended vaccinations. In the UK the usual vaccination protocols would typically ensure that cats are routinely vaccinated against these cat flu causing viruses. 

Typically, cats are vaccinated against feline calicivirus, feline herpes virus and feline panleukopenia, this is sometimes given alongside feline leukaemia vaccine. Kittens are usually vaccinated at nine and twelve weeks of age, this is because they are born with some immune protection which is passed on from their mother. If the kitten is vaccinated at too young an age their immune system may not respond fully, which is why the guidance is to give the first vaccine at nine weeks of age. 

In high risk situations such as a cattery environment this protocol may be adapted. After the initial primary vaccination course comprising of two vaccinations is given, an annual booster vaccination is administered thereafter. Adult cats at high risk require an annual booster vaccination to ensure their immunity levels remain high. Over time antibody levels will wane, however receiving the annual booster vaccination counters this. A cat who is at very low risk may only need vaccinating every 3 years.

Vaccines will be given in accordance with manufacturers’ recommendations, with certain disease components offered every three years, whilst others need to be given annually. 

Your veterinary surgeon will be able to advise you on the required vaccinations for your kitten or cat. The vet will take into account your cat’s lifestyle and risk factors when deciding on a vaccination plan. Although cat flu can be a very troublesome and unpleasant illness, in most cases vaccination of your cat will ensure that they are protected and remain healthy.

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