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Current Vaccination Protocols for Cats

Vaccination of our cats and dogs is absolutely essential to protect them from viral infections that can cause serious disease, and sometimes even death. 

Kittens are especially prone to contracting the sometimes-life-threatening viruses that we routinely protect against.

As more studies have been completed on the efficacy of vaccinations, the protocols for re-vaccinating our pets has changed over the years. Being a new cat owner and slightly confused about what is a core and non-core vaccine, we asked Dr. Louisa Fenny from Holistic Vet at Home to outline the latest guidelines for us.


Whilst it is imperative to complete the full course of kitten vaccinations, it may not be necessary to give a vaccination booster every single year.

However, having a vaccination protocol tailored to your individual pet and utilising vaccination titre-testing from a reputable source is essential.

It is also vital that pets receive a full veterinary health check at least once a year to enable early detection of disease. For older cats over the age of 8, a health check at least every 6 months is recommended. For pets with disease conditions, a check-up every 3 months or as directed by your Vet is important.

Cats are unique in that they are very good at hiding symptoms of disease hence by the time you notice any changes, the disease can already be advanced, hence early detection is key.

The vaccination protocol best suited to your pet will depend on a number of factors that include:
✔️ the pet’s individual immunity and health status
✔️ the age and presence of maternally derived antibodies (MDA)
✔️and the environment. 

Some environments have a greater risk of infection due to lower herd immunity and increased disease prevalence which will be discussed below. 

The following summarises the findings from the WSAVA (World Small Animal Veterinary Association) Vaccination Guidelines of 2015. This paper was completed by the Vaccination Guidelines Group (VGG), who are experts in the fields of small animal microbiology, immunology and vaccinology.

When researching what is best for your pet, it is always best to use reputable resources such as these rather than the various non-credible sources that you will find on the internet. Your veterinarian will also understand the disease prevalence in your particular area which is important in designing an appropriate vaccination protocol.

How Does Vaccination Work?

Vaccines are like a training course for the immune system. They prepare the body to fight disease without exposing it to disease symptoms.

When foreign invaders such as a virus enters the body, immune cells called lymphocytes respond by producing antibodies, which are protein molecules. These antibodies fight the invader known as an antigen and protect against further infection. A healthy cat can produce millions of antibodies a day, fighting infections on a continual basis.

Unfortunately, the first time the body faces a particular invader, it can take several days to ramp up this antibody response. For really nasty antigens like some viral infections, a few days is simply too long. The infection can spread and cause serious injury or even death before the immune system has had the chance to fight back.

That's where vaccinations come in. Vaccines are made of dead or weakened antigens that give the body a “practice run” at fighting the infection. They can't cause an  infection, but the immune system still sees them as an enemy and produces antibodies in response. After the threat has passed, many of the antibodies will break down, but immune cells called memory cells remain in the body.

When the body encounters that antigen again, the memory cells produce antibodies fast and strike down the invader before it's too late.

The Role of Maternally Derived Antibodies (MDA’s)

MDA’s provide protective immunity from the mother’s milk, transferred to the kitten (or puppy) via the colostrum which is the first milk. These maternal antibodies provide essential protection to the newborns during their first weeks whilst their own immune system is developing.

However, the MDA’s also prevent the pup or kitten from lodging their own immune response – and also from responding to vaccines. Knowing exactly when a vaccine will be effective in any given kitten is difficult.

For example, the runt of the litter (the last born and often the smallest and weakest) that received less colostrum might be capable of responding to vaccination at 8 weeks of age. However, a stronger kitten whom received more colostrum may still have circulating MDA which is blocking their own immunity (and hence the effects of the vaccination) until 12-16 weeks.

This is why it is recommended that the final dose of core vaccines for kittens be given at 16 weeks of age or older

Kitten Arya receiving her fourth booster shot at 16 weeks at Hornsby Heights Veterinary Hospital
An alternative to this last vaccination is performing a titre test to check if they are adequately immunised, which is discussed below. 

What is Herd Immunity?

When the population level of immunity (the ‘herd immunity’) falls below about 65%, there is a risk of outbreaks of that infectious disease. Vaccinating your pet therefore not only protects him or her from infection but is to the benefit of the entire cat population.

In areas where there is a lower herd immunity, your cat can be at increased risk of contracting infectious diseases. For example in rural areas with a higher prevalence of un-vaccinated, feral cats.

What are we protecting our cats against?

Here in Australia, we have core and non-core vaccination options available for cats.

Core vaccines are recommended for all cats regardless of their lifestyle or risk factors and include protection against feline panleukopenia, feline herpes virus and feline calicivirus.

Non-core vaccines are only given to cats who are in specific risk categories. These include vaccinations that protect against feline leukaemia virus and feline immunodeficiency virus.

To determine your cats risk it is important that you discuss your cat’s lifestyle with your vet so the vaccine schedule can be tailored accordingly.

Core Vaccines

#1. Feline Panleukopenia Virus (FPV)

Feline panleukopenia, otherwise known as Feline Infectious Enteritis or Feline Parvovirus is a life-threatening illness that is most commonly seen in young kittens

It has a very fast onset of symptoms such as a high temperature, loss of appetite, depression, vomiting, diarrhoea and rapid weight loss. Sadly, fatalities are common. 

It is a highly contagious virus and can persist in the environment for long periods. Vaccination is highly effective in protecting against infection from feline panleukopenia. 

#2. Feline herpesvirus (FHV-1) and feline calicivirus (FCV)

These viruses cause a condition called “cat flu”. Symptoms of cat flu include sneezing, coughing, discharge from the eyes and nose, a loss of appetite and sometimes ulcers on the tongue and eyes. 

This can lead to severe dehydration and debilitation and in severe cases pneumonia and death. 

Both viruses are easily spread through direct contact between cats, or via contaminated food bowls, bedding or on a person’s hands. After recovering from infection, some cats can become a carrier of the virus and remain contagious to other cats for months afterwards.

Both of these two viruses are very common and given the severity of symptoms that many cats develop, vaccination is important for all cats. Although vaccination for feline herpesvirus and feline calicivirus does not always prevent infection, it will help greatly in reducing the severity of symptoms if a vaccinated cat does become infected.

An F3 vaccine will provides protection against all three of these viruses.

Kittens usually receive their initial vaccination between 6-8 weeks of age, and then require booster vaccines given at 12 weeks of age and 16 weeks of age.

Another option is to wait until 16 weeks to give the vaccination, which is when the MDA’s will have worn off. This may be an option for low-risk kittens that are not in contact with other kittens or cats and in a low-risk environment, and is best discussed with your vet.

A first annual booster can be given 12 months later to ensure a good level of immunity, or a titre test can be performed at 16 weeks then again 12 months later.

After that the frequency of the booster vaccination varies depending on the titre test results, along with the individual risk of the cat. Pending the titre-rest results, re-vaccination may not be necessary for 1-7 years, however it is important to repeat the titre-test every 1-3 years depending upon the result of the test.

It’s also a good idea to have a general health profile blood test conducted at the same time to enable early detection of disease.

Non-core Vaccines

#1. Feline leukaemia virus (FeLV) 

This an important retroviral infection that can occur in cats. It is a member of the same virus family as feline immunodeficiency virus (FIV).

The most common effect of FeLV infection is immunosuppression. The virus infects the cells of the cat’s immune system by killing or damaging them. This leaves the cat vulnerable to a wide variety of other diseases and secondary infections. Cats that are persistently infected with FeLV have an increased risk of developing cancers such as lymphoma and leukaemia, as well as severe anaemia.

FeLV is spread via the saliva, especially during cat fight bites.

Vaccination is recommended in situations where cats have a high risk of exposure to the virus. This includes:

  • any cat that goes outdoors unsupervised or that
  • mixes with a cat that goes outdoors unsupervised or that 
  • mixes with a cat of unknown FeLV status (such as a rescued stray).
Kittens need two injections that can be given at the same time as normal kitten vaccination course. Adult cats also need two injections initially but require blood testing first to make sure they haven’t already contracted the infection. Boosters can then be given every 2-3 years.

#2. Feline immunodeficiency virus (FIV)

Feline immunodeficiency virus (FIV) is a retrovirus closely related to the human immunodeficiency virus (HIV). FIV is not transmissible to humans. FIV is endemic in domestic cat populations worldwide. The virus doesn’t survive long in the environment and loses its infectivity quickly once outside the host and is susceptible to all disinfectants.

The virus is transmitted through the blood and saliva of infected cats. The most common way for FIV infection to occur is via a bite wound sustained during a cat fight

This allows the saliva of an infected cat to enter the bloodstream of an uninfected cat. The risk of your cat becoming infected can be reduced by decreasing its chance of fighting with other cats. Methods to help reduce fighting include making sure your cat is sterilised and kept indoors at night, or, ideally only allowed outside access into a fully enclosed “cat run”.

The risk of transmission is very low in households with socially well-adapted cats. FIV cannot be spread through sharing feed or water bowls, litter trays or bedding with other cats in the house. Transmission from mother to kittens may occur, especially if the queen is undergoing a recently acquired infection. Infection with FIV is life-long as there is no known cure.

Vaccination is an option that is suitable for some owners to try and prevent their cat becoming infected with FIV. The initial vaccination course involves administering three injections at two weekly intervals (6 weeks in total).

Unfortunately the vaccination only covers for two strains of FIV and offers approximately 82% protection at best. It is generally only recommended that the FIV vaccination is given to high risk cats, such as cats that fight despite their owners’ best efforts.

It is also essential to test for FIV with a blood test prior to vaccinating. If your cat may have been vaccinated for FIV previously, the blood must be sent to an external lab for testing which can differentiate between FIV infection and an earlier vaccination.

Preventing Over-Vaccination of Cats

Whilst vaccination in general is considered very safe, vaccine associated adverse events are possible. Every time a vaccination is administered, it places a strain on the immune system. 

This can sometimes cause problems with pets with any immune-mediated disease conditions which includes skin allergies, thyroid conditions, IBD (Feline inflammatory bowel disease) and many others. From the WSAVA vaccination guidelines: “Vaccines themselves do not cause autoimmune disease, but in genetically predisposed animals they may trigger autoimmune responses followed by disease – as can any infection, drug, or a variety of other environmental factors.” 

Therefore, we should aim to reduce the vaccine load on pets, provided this does not increase the risk of disease.

What is a Titre Test?

This is a simple blood test that can determine whether your cat still has immunological protection against FPV, FHV1 and FCV. If they do, revaccination is unnecessary.

It is important to note that there are in-house titre tests available as well as those available from an external laboratory. Whilst a little more expensive, the external lab testing is far more accurate and hence recommended.

Currently there are no international guidelines to suggest how long we can expect a high titre to stay high for the average cat. Current advice is that testing should performed every 1-3 years, but in cats older than 8 years, this should be done annually. Cats of this age and older will also benefit from an annual general health profile blood test for early detection of disease. 

written by Dr Louisa Fenny, June 2019 for Australian Cat Lover (all rights reserved).

References and further reading

About the writer

Dr Louisa Fenny is a Perth-based Veterinarian and owner of Holistic Vet @ Home. She is passionate about fresh and natural nutrition and utilising Veterinary Western Herbal Medicine to prevent and treat disease.

Dr Lu is pictured here with her 2 recent “Foster Fails” named “Bubbles” and “Mini-Cat”.

These kittens were brought into the Pets & Vets WA clinic - Karratha as stray kittens during the filming of Desert Vet TV – a four-part series filmed in Western Australia’s Pilbara Region that stars not only Lu but also her veterinarian dad Dr Rick Fenny and her brother Ed.

It will air on Channel Nine in Australia in the second half of 2019.

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