All of us are urged to vaccinate our cats, to prevent them getting some serious and often fatal diseases. But every so often, one hears of dangers with respect to vaccines – usually minor side effects, but even sometimes even more serious reactions. So can the usual cat vaccinations ever be harmful? What are the risks of the side effects of vaccinations, versus the risk of leaving your cat unprotected against potentially fatal diseases? Let us take a look at the available evidence.
In the UK, cats are usually vaccinated against Feline Influenza (Cat 'flu) and Feline Infectious enteritis (FIE). They are also sometimes vaccinated against Feline leukaemia virus (FeLV) and Feline chlamydiosis. Cat 'flu is extremely common, and FIE, while much rarer, still occurs from time to time. The other diseases are less common, but this could be due to the fact that many cats are now vaccinated against them.
Kittens usually receive all these vaccines as a single combination dose, which is typically given to them in two separate vaccinations three to four weeks apart. They tend to get the first dose at around eight weeks of age, although anything from six to sixteen weeks is normal. They then get a booster one year later and then every year after that..
Rescued cats are usually given a thorough examination and they will be tested to see if they have any of these diseases already. They are then given the full vaccination course before they are they are re-homed.
There are certain risks where all vaccinations are concerned. However, this risk needs to be weighed up carefully and then balanced against the significant role certain vaccines have played in preventing cats from developing serious infectious diseases and thus living longer and healthier lives. But vaccine reactions do occur. They include immediate allergic reactions, and also some reactions which occur a few days or a few weeks later. Longer term problems such as chronic skin conditions, arthritis, immune system disorders, and epilepsy have been connected to vaccine reactions in the past. However, it is difficult to be certain about these, since other factors such as genetics, diet, and lifestyle may all play a part. And since so many cats have vaccinations, a proportion will probably be unwell after their vaccinations...and at any other time too! So are any serious side effects caused by vaccinations? No-one is really certain about this.
A specific issue in cats that can occur is an injection site sarcoma, a type of cancerous tumour that can develop in response to any injection under the skin. This received a great deal of publicity at one time, was said to be related to the feline leukaemia vaccination, and is possibly responsible for many owners deciding not to vaccinate their cats against this particular disease. Of course, any swelling that persists for more than a few days at the site of an injection should be checked over by a vet, as should any other lump or bump which appears. But severe reactions such as this are thought to only occur in approximately one in every 10,000 cats vaccinated.
The diseases against which we vaccinate have definitely not gone away, as some owners think. As stated above, Feline Influenza is still common, and Feline Infectious Enteritis still occurs from time to time. Feline Leukaemia is not common, but it does occur, and it is almost invariably fatal. So it really is necessary to vaccinate against these conditions. Indoor only cats are less likely to get them than those cats which roam freely, but they may still pick them up. Also, any cats which are being shown are required to be vaccinated, and all boarding catteries require up-to date vaccinations.
One way of minimising the already slight risk is to give boosters less often than every year. Individuals respond differently to vaccinations, and there are differences in how long immunity will last. Vaccine manufacturers try to estimate how long antibodies against the disease will last, but they always err on the side of caution. For this reason, some vets now recommend giving the first booster a year after the initial vaccination course, but then only giving boosters every three years. But of course, this may not be enough for all cats. Also, cat shows and boarding catteries still require yearly boosters.
The number one protection that any animal can have is a healthy body, which means a good diet, and suitable lifestyle, freedom from parasites, and freedom from stress. But like people, cats can still catch infectious diseases occasionally, however healthy they are.
Of course, one alternative is not to vaccinate, and simply to treat any disease if and when it occurs. This may be a viable option in the case of cats which lead a very sheltered life, particularly if they are elderly and/or the stress of vaccination might cause harm.
Homeopathic vaccination, or 'nosodes' are becoming more widely known, and several studies have shown that they be effective. But the studies have been quite small, and many vets would question whether homeopathic nosodes do any good at all. Nevertheless, they are probably a good idea for cats which have previously had a severe reaction to vaccines, and for those whose owners have decided not to vaccinate for some other reason. While they have not been proved to do any good, they can certainly do no harm.
Ultimately the decision has to be the owner's. Vaccinations can occasionally be harmful, but the risks are definitely less than those associated with the diseases which the vaccines are designed to prevent. Vaccinations still have the backing of the majority of the veterinary profession, and are necessary if you are ever going to put your cat into a boarding cattery...and any of us might have to do that in an emergency. So for all these reasons, regular vaccination continues to be recommended.