General Health: Vaccinations – Tanya's Comprehensive Guide to Feline Chronic Kidney Disease

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Overview

Vaccinations can be very important for feline heath, but many people with CKD cats worry about whether to continue vaccinating their cat.
This page discusses vaccinations and ways to reduce any possible risks.

What are Vaccinations?

Vaccinations protect cats from certain infectious diseases. They do this by stimulating the cat’s immune system to develop antibodies towards the disease, so the cat’s immune system will try to fight off the disease should it be exposed to it in the future. The immune response to vaccination: a brief review (2013) Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 explains more about how vaccines protect cats from infection.

Kittens are normally given a series of vaccinations, and then cats are revaccinated throughout their lives, with the frequency varying depending upon the type of vaccine used and the legal requirements of the area where the cat is located.

The American Veterinary Medical Association explains more about how vaccinations work and the benefits they offer.

Cornell University College of Veterinary Medicine explains the benefits and risks of vaccinations.

2013 AAFP Feline Vaccination Advisory Panel report (2013) Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 pp785-808 are an earlier version of the guidelines.

Guidelines for the vaccination of dogs and cats compiled by the Vaccination Guidelines Group (VGG) of the World Small Animal Veterinary Association (WSAVA) (2016) Day MJ, Horzinek MC, Schultz RD & Squires RA Journal of Small Animal Practice 57 ppE1-E45 also offers detailed vaccination guidelines.

The 2020 guidelines say the 2013 and 2016 guidelines “should still be considered relevant and actionable complements to the 2020 guidelines.”

This section explains more about core vaccinations and their benefits and risks, particularly for CKD cats.

Types

There are a number of vaccinations available for cats. Cornell University College of Veterinary Medicine provides an overview of the main feline vaccines, including non-core vaccines.

The following are the core vaccines which are usually offered to CKD cats (rabies is not offered in the UK unless the cat is going abroad):

FVRCP

These are the core vaccinations given to kittens, and then topped up over the course of the cat’s life.

FVRCP vaccinates the cat against three feline diseases. FVRCP stands for:

Initial	Refers To	Notes
F	Feline
VR	Viral Rhinotracheitis	Caused by the feline herpes virus (FHV-1)
C	Calicivirus (FCV)
P	Panleukopaenia (FVP)	Also known as distemper or parvovirus

The FVRCP vaccine was usually given several times to kittens a few weeks apart; it was then given once yearly in countries such as the UK and once every three years in countries such as the USA (see Frequency). However, 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 now advise that following the initial series of vaccinations given to kittens, the first top up should be given at six months of age, then three yearly thereafter. The six monthly shot may not be necessary if you are using an intranasal vaccine, but annual vaccination will be required.

Viral Rhinotracheitis and Calicivirus

Viral rhinotracheitis (which is caused by the feline herpes virus) and calicivirus are both upper respiratory tract viral infections. In the UK they are sometimes colloquially referred to as “cat flu.”

This vaccine can be helpful against these viruses, though may not bestow complete immunity. Cornell University College of Veterinary Medicine says “Protection induced by the currently available vaccines minimizes the severity of disease, but does not prevent disease in all cats.” Two of my cats who had been vaccinated did develop upper respiratory tract infections at different times and were thoroughly miserable. However, their illnesses lasted less time and were less severe than that developed by the rescue cat I had just adopted who had not yet finished his course of vaccinations.

Disease information fact sheet feline herpesvirus 1 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 has an overview of the feline herpesvirus.

Disease information fact sheet felinecalicivirus 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 has an overview of the feline calicivirus.

Vaccination of cats against infectious upper respiratory disease (2013) Ford RB Today’s Veterinary Practice Nov/Dec 2013 explains more about feline upper respiratory viruses and vaccines. Some of the photos of infected cats should give you pause for thought if you are opposed to vaccinations.

Panleukopaenia

Panleukopenia is also known as distemper. It is a nasty disease which is often fatal, particularly in kittens. Fortunately it is much less common since vaccination was introduced (the vaccines are highly effective), but since it can survive in the environment for years, unvaccinated cats may be at risk.

Disease information fact sheet: feline panleukopenia 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 has an overview of the feline panleukopenia virus.

Feline panleukopenia guidelines (2015) Hartmann K European Advisory Board on Cat Diseases has some information on panleukopenia.

Rabies

Rabies is a serious disease that can kill both cats and humans. Therefore the rabies vaccine is a legal requirement in many countries throughout the world. It is not given routinely in the UK, where rabies does not exist, though it may be given there to cats who travel outside the UK (my cats had to have it before they could fly to the USA).

Disease information fact sheet rabies 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-2 has an overview of the rabies virus.

Formulations

There are three main forms of vaccine available:

inactivated (killed)
modified live (attenuated)
recombinant

As you might expect, a killed virus contains a dead form of the virus, so it will also contain an adjuvant to make it work. The adjuvant is added to create inflammation and thus stimulate an immune response to the vaccine. Adjuvants and vaccines Center for Disease Control and Prevention explains more about adjuvants. Modified live and recombinant vaccines do not contain adjuvants.

Unfortunately, in cats it appears that the use of vaccines containing adjuvants may result in a higher risk of developing a form of cancer known as FISS or feline injection site sarcoma (previously known as VAS, or vaccine-associated sarcoma). Veterinary Partner says that the adjuvant “holds the virus in the area of the vaccination for a couple of weeks so it can be released slowly, allowing immune stimulation to take place over a longer time period. This kind of stimulation can lead to local inflammation in the area of vaccination and one theory is that this inflammation is what leads to precancerous changes in the local cells. Indeed, some fibrosarcomas have been found to have vaccine adjuvant embedded within them.”

However, 2013 AAFP Feline Vaccination Advisory Panel report 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 pp785-808 say “Although initial reports linked development of sarcomas at vaccination sites with the use of inactivated rabies or FeLV vaccines, and aluminum-based adjuvants, more recent studies found no relationship between vaccine type, brand or use of inactivated versus modified-live vaccines and the risk of subsequent sarcoma formation.”

2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 state “the Task Force believes there is currently insufficient research to justify recommending a single vaccine type.”

Nevertheless, Vaccination of cats against infectious upper respiratory disease (2013) Ford MB Today’s Veterinary Practice Nov/Dec 2013 pp57-61 says “Modified-live virus (nonadjuvanted) vaccine is recommended over killed virus products for routine use. Use of killed (adjuvanted) virus vaccine is reserved for use in pregnant queens, retrovirus positive cats, or in high-density populations, where there is minimal evidence of respiratory disease.”

Pet Place discusses which vaccine to choose.

Benefits and Risks

Benefits

The main benefit, of course, is that the cat is protected against illnesses that at best can make him/her very poorly and at worst could kill.

Risks

Two disadvantages of vaccination are the cost and, the fact that some cats may be under the weather for a few days after receiving vaccinations. 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 say “The most commonly reported vaccine reactions are lethargy, anorexia and fever for a few days after vaccination, or local inflammation at the site of injection.” However, I would say this small risk of being under the weather for a few days is worth it for the protection which vaccinations bring.

Other potential risks are as follows:

Link to CKD

In 2002 a tentative connection between feline vaccinations and CKD was mooted. The connection arises because feline vaccines are grown on kidney cells known as Crandell Reese Feline Kidney (CRFK) cells. It has long been known that growing the vaccines in this way produces some unidentified antibodies in addition to those required for the vaccine, but it was only discovered in 2002 that the unidentified antibodies were to renal tissue. These additional antibodies occur in all modified live or killed vaccines, but do not occur with intranasal vaccines. In the UK, live vaccines are usually used.

Investigation of the induction of antibodies against Crandell-Rees feline kidney cell lysates and feline renal cell lysates after parenteral administration of vaccines against feline viral rhinotracheitis, calicivirus, and panleukopenia in cats (2005) Lappin MR, Jensen WA, Jensen TD, Basaraba RJ, Brown CA, Radecki SV, Hawley JR American Journal of Veterinary Research 66(3) pp506-511 concluded that “hypersensitization with CRFK cell proteins did not result in renal disease in cats during the 56-week study.”

A slightly later study, Interstitial nephritis in cats inoculated with Crandell Rees feline kidney cell lysates (2006) Lappin MR, Basaraba RJ, Jensen WA Journal of Feline Medicine and Surgery 8(5) pp353-6, found that 50% of the cats in the study who were given normal vaccines developed interstitial nephritis according to biopsies. However, these cats were vaccinated 12 times in 50 weeks, which is obviously far more often than is normal (the current US guidelines are for cats to be vaccinated only once every three years). One group of cats in the study were given intranasal vaccines, and they did not develop any signs of interstitial nephritis.

Risk factors for development of chronic kidney disease in cats (2016) Finch NC, Syme HM & Elliott J Journal of Veterinary Internal Medicine 30(2) pp602-10 states “A large proportion of the feline population receives regular vaccinations and, based on findings from previous studies described above, this practice may be considered a potential risk factor for CKD in cats.” It concludes “Our study suggests independent associations between both vaccination frequency and severity of dental disease and development of CKD” and states that further studies are necessary to investigate why this might be the case.

In 2012 Dr Lappin stated that in his research cats who developed antibodies did not go on to develop CKD. He recommends that core vaccines should continue to be given to healthy cats in accordance with the American Association of Feline Practitioners vaccination guidelines, which are available as 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265.

Feline Injection Site Sarcoma (FISS)

Many people are concerned about the risk of a cancer called feline injection site sarcoma (FISS), which is primarily associated with the rabies vaccine (and with the feline leukaemia vaccine), though it may also be seen following FVRCP vaccinations or other injections.

FISS is extremely rare — Vaccines and sarcomas: a concern for cat owners American Medical Veterinary Association explains more about FISS and states that the rate is about one cat in every 10000-30000 (a rate of 0.01-0.003%) — but that is not much consolation if it is your cat who is affected.

2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 recommend that “veterinarians and owners monitor the vaccination site for swelling or lumps using the “3-2-1″ rule.” This basically means that the lump should be biopsied if: it is present three months after vaccination; is larger than two cm in diameter; or is increasing in size one month after vaccination.

FISS is difficult to treat because the tumour has to be medically excised, and it is necessary to go in very deep. For this reason some vets give vaccinations in a limb rather than the main body, for the rather morbid reason that the cancer can be more easily treated via amputation of the affected leg.

Some vets give vaccinations in the tail, on the basis that it is easier for a cat to manage without a tail than a limb. Tail vaccinations in cats: a pilot study (2014) Hendricks CG, Levy JK, Tucker SJ, Olmstead SM, Crawford PC, Dubovi EJ & Hanlon CA Journal of Feline Medicine and Surgery 16(4) pp275-280 found that vaccination in the tail was effective and states that should it be necessary, “tail amputation is minor surgery that can be performed by a general practitioner on an outpatient basis.” Tail vaccination in cats: balancing disease protection and cancer treatment (2013) University of Florida College of Veterinary Medicine discusses the study.

If you decide to have your cat vaccinated in the tail, ensure it is done correctly. 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 state that “vaccinations must be administered in the distal tail, something that may not be practical for most clinicians.”

Veterinary Partner discusses FISS and how to treat it.

Feline injection-site sarcoma: then and now (2013) Ford RB Today’s Veterinary Practice Jul/Aug 2013 pp54-57 explains more about how and why FISS began and how to treat it.

Feline injection site sarcoma guidelines 2015, updated 2021 (2021) Hartmann K & Hirschberger J European Advisory Board on Cat Diseases discuss prevention and management of FISS and state that additional treatments are usually needed in addition to removal of the tumour, such as radiation therapy.

Treatment of feline injection-site sarcoma with surgery and iridium-192 brachytherapy: retrospective evaluation of 22 cats (2020) Bloch J, Rogers K, Walker M, Dawson J & Wilson-Robles H Journal of Feline Medicine and Surgery 22(4) pp313-321 looked at implanting radioactive iridium to deliver radiation therapy to any tumour remaining after surgery. The study found that while there were some complications (the surgical wound opened in 77% of the cats), overall the treatment appeared to be as effective as traditional radiotherapy performed after surgery.

Feline injection site sarcomas: risk factors, diagnosis, staging, and treatment algorithm (2021) Intile J & Gareau A Today’s Veterinary Practice Jul/Aug 21 examines

Tufts University Cummings School of Veterinary Medicine (2018) reports on research into the use of a cancer medication called carboplatin to treat FISS.

Whether to Vaccinate

Many people are reluctant to vaccinate their CKD cats, and some people are reluctant to vaccinate any of their cats, healthy or otherwise. This is usually because of concerns about frequency of vaccination (there is some debate about whether cats really need to be vaccinated annually) and fear of the cat developing FISS.

Vaccination decisions need to be tailored to the individual cat. 2013 AAFP Feline Vaccination Advisory Panel report 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 pp785-808 says “Vaccination is a medical procedure, and the decision to vaccinate, even with core vaccines, should be based on a risk/benefit assessment for each cat and for each vaccine antigen. Vaccination may indeed be beneficial, but it is not innocuous, and the benefit of vaccinating an animal (eg, the induction of clinically meaningful immunity) must be balanced against the risk of adverse events, likelihood of exposure and severity of disease. Where practical, every effort should be made to ensure that cats are healthy prior to vaccination; however, concurrent illness should not necessarily preclude vaccination.”

Healthy Cats

Most healthy cats can receive vaccinations, though they may not be appropriate for cats receiving corticosteroids. Feline panleukopenia guidelines (2015) Hartmann K European Advisory Board on Cat Diseases says “In cats receiving corticosteroids, vaccination should be considered carefully. Depending on dosage and duration of treatment, corticosteroids may cause functional suppression of particularly cell-mediated immune responses, but pertinent studies are lacking.”

Antibody response to feline panleukopenia virus vaccination in healthy cats (2017) Bergmann M, Schwertler S, Reese S, Speck S, Truyen U & Hartmann K Journal of Feline Medicine and Surgery 20(12) pp1087-1093 gave FVRCP vaccinations to 112 cats who had previously been vaccinated less than twelve months earlier. Titres (see below) were checked before modified live FVRCP vaccination and then again after seven days and after 28 days. It found that only 48.3% of the cats in the study had an adequate response to the panleukopaenia part of the vaccination (defined as a fourfold titre increase). The study mentions that humans with CKD may be less likely to develop antibodies following vaccination, but it is not known if the same is true of cats. The cats in the study were more likely to respond if they had a low titre beforehand or had not been vaccinated previously. DSH cats responded better than purebreds. The study concludes “As none of the cats with high pre-vaccination antibody titres (≥ 1:160) had an at least four-fold increase in FPV antibody titres, measurement of antibodies rather than regular revaccinations should be performed. Thus, evaluation of FPV antibody titre in cats with previous vaccinations against FPV are recommended prior to revaccination.”

This study did only use one kind of vaccine (modified live) and collected data in a limited area. Nevertheless, it may support the idea that vaccinations, at least of the type used in the study, should not be given too frequently.

CKD Cats

The caution details on a feline vaccine packet state that the vaccine is for administration to healthy cats only. CKD cats are by definition not healthy, so it used to be advised that they should not receive vaccinations. Once Thomas had been diagnosed, my vet said she did not recommend giving him vaccinations, so we stopped.

Recent guidelines take a different approach, recommending that cats with chronic but stable conditions (such as CKD) should in fact be vaccinated. 2013 AAFP Feline Vaccination Advisory Panel report (2013) Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 pp785-808 say “Whether older cats respond to vaccination in the same manner as younger animals do is inadequately studied. In the absence of data, the Advisory Panel recommends that healthy older cats and those with chronic but stable disease conditions receive vaccines in the same manner as younger adults. Less frequent vaccination is not advised due to inherent immunosenescence.”

Feline panleukopenia guidelines (2015) Hartmann K European Advisory Board on Cat Diseases says “In cats with chronic illnessvaccination may sometimes be necessary.Manufacturers evaluate vaccine safety and efficacy in healthy animals and accordingly label their vaccines for use in healthy animals only. Nonetheless, cats with stable chronic conditions such as chronic renal disease, diabetes mellitus or hyperthyroidism should receive vaccines at the same frequency as healthy cats. In contrast, cats with acute illness, debilitation, or high fever should not be vaccinated, unless there are compelling reasons to do so. In these cases, inactivated preparations should be used.”

One thing to bear in mind when considering whether to vaccinate a CKD cat is the fact that the cat is visiting the vet more often and thus being exposed to other patients with these viruses. 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 say “indoor only cats may also be exposed to infectious agents when brought to a veterinary clinic for a wellness examination. In theory, strictly indoor cats may be more susceptible to developing some infectious diseases (such as FPV and FCV infection) than cats with outdoor access because they may not receive “natural boosting of immunity” that occurs with natural exposure.”

This is a particular concern for CKD cats because they are immune-compromised, and non-vaccinated cats are therefore more vulnerable to catching the viruses against which core vaccines offer protection, especially if they are older (as most CKD cats are). The immune response to vaccination: a brief review (2013) Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 say “While only limited feline-specific data exist, we know collectively from other species that, with age, the immune system undergoes profound changes resulting in an overall decline in immune function known as immunosenescence…Age-related declines in immune function directly translate into increased susceptibility of aged patients to infection, autoimmune disease and cancer.”

Titre Testing

Some people decide whether to give their cats vaccinations, particularly rabies vaccinations, by having titre testing done. This measures current levels of immunity so a decision can be made whether or not to revaccinate.

Centers for Disease Control and Prevention says “A rabies antibody titer is essentially an estimation of an immune response against rabies virus (either through exposure or vaccination). The RFFIT is one method which provides a laboratory measurement of the ability of an individual human or animal serum sample to neutralize rabies virus.” Kansas State University Veterinary Diagnostic Laboratory has more information about the RFFIT test. The test costs US$73 if you submit it directly to KSU.

There is no accepted titre level for proven efficacy. It should be remembered that titres only show a level of antibodies, but a positive level does not mean guaranteed protection against the virus in question. However, it may be reassuring if you opt not to give your cat vaccinations to have some indication as to whether your cat appears to have some residual immunity conferred by earlier vaccinations.

Titre testing will not exempt your cat from any legal requirements. One of my cats who had previously been through six months of UK quarantine had a rabies titre level that was ten times higher than that needed for a UK pet passport, but it was irrelevant: her rabies vaccinations had lapsed so we had to act as if she had never received any rabies vaccinations before and start from scratch.

Antibody titers versus vaccination (2013) Ford RB Today’s Veterinary Practice May/Jun 2013 pp35-39 has an excellent overview of the role of titres.

Minimising the Risks

I understand that many people are very concerned about whether or not to vaccinate their CKD cats. There are ways to minimise the risks, as follows:

Minimising the Risk: FVRCP

Here are some suggestions for minimising the possible risks of the FVRCP vaccine.

Frequency

In the USA, it is relatively common for vets to give core vaccines only once every three years. In the UK, many vets still continue to offer annual vaccinations. This may be because historically, the USA used killed vaccines whereas the UK used modified live vaccines, so the risk of FISS was thought to be much lower in the UK.

Vaccination of cats against infectious upper respiratory disease (2013) Ford RB Today’s Veterinary Practice Nov/Dec 2013 says that for adult cats “All cats should be revaccinated 1 year following completion of the initial series. Revaccination no more often than every 3 years is recommended for household pet cats living in low-density environments. Annual revaccination is indicated for cats housed in high-density environments, where risk for exposure to respiratory disease is high.”

However, 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 now advise that following the initial series of vaccinations given to kittens, the first top up should be given at six months of age, then three yearly thereafter. The six monthly shot may not be necessary if you are using an intranasal vaccine, but annual vaccination will be required.

Despite these guidelines, you will probably still be offered annual vaccinations if you are outside the USA and Canada. This is because that is what the manufacturers recommend. Disease information fact sheet feline herpesvirus 1 2013 Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 states “”manufacturers recommend revaccination after 1 year. Published serologic and challenge studies indicate, however, that vaccination provides moderate protection in the majority of animals for up to 3 years or longer post-vaccination. Nevertheless, protection is not always complete shortly after vaccination and declines as the vaccination interval increases.”

Choosing not to vaccinate or to only vaccinate every three years in the UK can be problematic if your cat ever goes to a cattery, because catteries usually insist upon annual vaccinations. I asked my vet to write a letter to say vaccinations were not appropriate for Harpsie, and the cattery accepted this and allowed Harpsie to stay without recent vaccinations. However, 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 say “Cats entering boarding, breeding, foster, or shelter situations have increased risk of disease exposure as well as systemic stress. Vaccination may be warranted prior to entering these environments when possible.”

The immune response to vaccination: a brief review (2013) Scherk MA, Ford RB, Gaskell RM, Hartmann K, Hurley KF, Lappin MR, Levy JK, Little SE, Nordone SK & Sparkes AH Journal of Feline Medicine and Surgery 15 Supp pp1-3 say “Memory responses to vaccine antigens in aged patients, while less robust than in young adults, appear to be sufficient enough to maintain protective levels of antigen-specific antibody in the majority of cases. If a cat is routinely immunized through its adult years then maintaining vaccination protocols at recommended intervals is warranted in senior cats. Intervals do not need to be decreased because titers are likely to be maintained between boosts; however, intervals should not be increased either due to immunoscenescence.”

Vaccine Formulation Choice

Feline panleukopenia guidelines (2015) Hartmann K European Advisory Board on Cat Diseases says “In immunocompromised individuals, inactivated FPV vaccines are recommended. Modified live FPV vaccines should be used with caution in severely immunocompromised individuals, as the failure to control viral replication could potentially lead to clinical signs.”

Minimising the Risk: Rabies

Use a vaccine at room temperature. Refrigerated vaccines have been associated with a higher rate of FISS according to Feline injection site sarcoma guidelines 2015, updated 2019 92019) Hartmann K & Hirschberger J European Advisory Board on Cat Diseases.

Some vets give vaccinations in the tail, on the basis that it is easier for a cat to manage without a tail than a limb, should amputation be necessary because of FISS. Tail vaccinations in cats: a pilot study (2014) Hendricks CG, Levy JK, Tucker SJ, Olmstead SM, Crawford PC, Dubovi EJ & Hanlon CA Journal of Feline Medicine and Surgery 16(4) pp275-280 found that vaccination in the tail was effective and states that, should it be necessary, “tail amputation is minor surgery that can be performed by a general practitioner on an outpatient basis.” Tail vaccination in cats: balancing disease protection and cancer treatment (2013) University of Florida College of Veterinary Medicine discusses the study.

Frequency

Many vets offer annual rabies vaccinations, often because local laws require these vaccines to be given this frequently. From a medical perspective, however, less frequent vaccination is recommended. 2020 AAHA/AAFP feline vaccination guidelines (2020) Stone AES, Brummet GO, Carozza EM, Kass PH, Petersen EP, Sykes J & Westman ME Journal of the American Animal Hospital Association 56(5) pp249-265 say of rabies vaccinations “When local laws/regulations permit, the Task Force recommends a 3-year vaccination interval using a 3-year labeled vaccine.”

The Rabies Challenge Fund supported studies at the University of Wisconsin School of Veterinary Medicine which were aimed at demonstrating that the requirement for rabies vaccinations every three years in many USA states is unnecessary, and that rabies vaccinations may confer sufficient immunity for five or even seven years in dogs. It is quite probable that they also last a long time in cats.

Discuss the best approach for your cat with your vet.

If you opt for three yearly vaccinations, you should still take your cat to the vet for regular (yearly minimum for healthy cats) check ups.

Vaccine Formulation Choice: PureVAX

Most rabies vaccines contain adjuvants, which have been associated with an increased risk of a form of cancer known as FISS.

The PureVAX feline rabies recombinant rabies vaccination is considered safer by many because it is non-adjuvanted. Make sure your vet knows you want your cat to be given the non-adjuvanted recombinant version rather than the killed vaccine.

This vaccine is available both as a one year and as a three year vaccine (rumour has it they are in fact one and the same and are simply labelled with different validities). Three year duration of immunity in cats vaccinated with a canarypox-vectored recombinant rabies virus vaccine (2012) Jas D, Coupier C, Toulemonde CE, Guigal PM & Poulet H Vaccine 309490 pp6991-6996 tested the effectiveness of the PureVAX rabies vaccine in cats and states “This vaccination regimen induced a strong and sustained antibody response, and all vaccinated animals were protected against virulent rabies challenge carried out 3 years after vaccination.”

This vaccine is normally acceptable for cats holding UK pet passports (though always check in case regulations have changed). My cats received the one year PureVAX rabies shots (the three year option was not available at the time) during the period when it was necessary for them to receive them and had no problems with them, despite being over the age of ten at the time.

The European Medicines Agency has more information about the PureVAX three year rabies vaccine.

Rabies Exemption USA

A few US states only require the rabies vaccine to be given every three years, but in others you may be required by law to have your cat vaccinated against rabies annually.

However, your state may permit your cat to be given a medical exemption from the rabies vaccination requirement. The following states permit exemptions in principle, though only on a case by case basis: Alabama, California, Colorado, Connecticut, Florida, Illinois, Maine, Massachusetts, Maryland, New Hampshire, New Jersey, Nevada, New York, Oregon, Pennsylvania, Vermont, Virginia and Wisconsin. The American Veterinary Medical Association has information about the particular requirements of each state but states “Advanced age of the animal or a desire on the part of the client or veterinarian to minimize the use of vaccinations (in the absence of a specific contraindication to vaccination) should not be considered sufficient justification for issuing a rabies vaccination waiver.”

A medical exemption (waiver) is merely evidence that you are in compliance with the law. The American Veterinary Medical Association says “a waiver only serves to allow the animal to be properly licensed in compliance with animal control regulations where this is allowed…If the animal with a rabies vaccination waiver is involved in a potential rabies exposure incident, the animal shall be considered unvaccinated against rabies for the purpose of enforcing appropriate public health regulations.”

If your cat bites somebody (e.g. your vet) in the USA, you will normally be asked to provide evidence of rabies vaccination. Some people who do not vaccinate their cats against rabies instead obtain titre measurements (see above), but in the USA no state currently accepts a rabies titre as the legal equivalent of rabies vaccination, so your cat would probably be subject to quarantine. This may be as short as ten days, and in some cases the quarantine may take place in your own home, but this is not always the case.

This is despite the findings of Compendium of animal rabies prevention and control (2016) National Association of State Public Health Veterinarians; Compendium of Animal Rabies Prevention and Control Committee; Brown CM, Slavinski S, Ettestad P, Sidwa TJ, Sorhage FE Journal of the American Veterinary Medical Association 248(5) pp505-517, which advises that cats overdue for a rabies vaccination who are exposed to rabies should have a rabies booster shot followed by an observation period rather than be subject to quarantine or euthanasia.

Dogs and cats overdue for vaccination — recommendations for updating immunizations (2012) Ford RB Today’s Veterinary Practice Nov/Dec 2012 pp26-32 explains what to do to bring your cat’s immunisations up to date.

What to Do if Your Cat Has a Reaction

Firstly, don’t panic. Minor reactions are not unknown. One of my cats was always under the weather for a few days after vaccinations, a bit lethargic and subdued. As long as your cat eats (assist feed if necessary) and drinks, you will probably find s/he is fine after a few days.

If you find a lump, also don’t panic. The chances of it being FISS are vanishingly small. You normally only need to be concerned if:

The lump has been present for more than three months after vaccination
The lump is growing
The lump is bigger than 1 inch (2cm) in diameter.

Even then, it might not be FISS, but of course you should consult your vet.

If your cat does develop FISS, some vaccine manufacturers may assist with your veterinary costs if you have complete vaccination records to support your claim. One member of Tanya’s CKD Support Group successfully did this.

This page last updated: 07 June 2022

Links on this page last checked: 05 June 2022