Does My Cat Need To Be Vaccinated Every Year?

Although most vaccine manufacturers recommend annual vaccination for feline “distemper” (panleukopenia) and the feline respiratory viruses (calicivirus and feline herpes virus), there is overwhelming scientific evidence that this is not necessary. The American Association of Feline Practitioners (AAFP) and the World Small Animal Veterinary Association (WSAVA) have issued specific guidelines regarding this issue. Their recommendations state that, following an appropriate initial vaccination protocol, the FVRCP (distemper/respiratory virus) vaccine need only be given every 3 years at most.

With regards to rabies vaccination, it is required by law in many counties. Following initial vaccination with a one year vaccine, we recommend three-year rabies shots.

It is important to note that whereas the rabies and distemper vaccines produce excellent protection against these diseases, the vaccines against the two respiratory viruses are not 100% effective. Cats still become infected, but the vaccine decreases the severity of the associated clinical signs. Both viruses are harbored for varying periods of time by infected cats. Calicivirus is usually carried for a few years at most, but feline Herpes virus remains in the cat’s nervous system for life. Periods of stress can reactivate this virus many years after the initial infection.

What about the feline leukemia vaccine?
The AAFP and the WSAVA do recommend vaccinating all kittens for feline leukemia (FELV). This recommendation is based on the fact that young cats are much more susceptible to this disease. The guidelines also recommend continued boosters for indoor/outdoor cats but they differ on how often these boosters should be given.

I have some reservations about the recommendation to routinely vaccinate all kittens against FELV. Although the feline leukemia virus causes a uniformly fatal disease, the incidence of the disease is low (it is currently estimated to be 2% in the general population). A cat contracts the disease either by living in close contact with cats that are positive for FELV or by being bitten by an FELV positive cat. They can also be born with the disease if the mother is infected. When a kitten first presents for vaccination he or she may have already been exposed in which case there is no evidence that vaccination would be of benefit. If the kitten has not been exposed and is not going to be an outdoor cat, I question the benefit of giving the vaccine. One noteworthy exception would be if the kitten or cat was going to live in a household with FELV positive cats. The recommendation to vaccinate outdoor cats is reasonable as they could potentially be exposed to FELV positive cats. If the cat only goes out in the yardunder supervision the need is less clear.

The reason for my concern about over vaccinating for FELV is that the leukemia vaccine is one of the two vaccines (the other being rabies) most commonly associated with the formation of a tumor at the vaccination site. The incidence of this tumor (called an injection site sarcoma) is VERY low (probably 1 in 10,000) but it is an EXTREMELY AGGRESSIVE TUMOR which is quite difficult to treat and will likely result in the death of your cat.

A separate issue relating to the vaccination of cats is that the viruses for almost all feline vaccines are grown in cell cultures composed of feline kidney cells. It has been shown that transient inflammation occurs in the kidneys of cats following vaccination, presumably due to the presence of feline kidney cell proteins in the vaccine. Given the extremely common occurrence of kidney disease in older cats questions have been raised as to whether the two are related. This has not yet been proven, but it is cause for concern. At Mahomet Animal Hospital we offer the only FVRCP vaccine that is not derived from viruses grown on feline kidney cell cultures.

Don’t hesitate to call if you have any questions about any of these issues.

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