| VAS: Vaccine Associated Sarcoma |
| Vaccine Tumors and Vaccine Recommendations for Cats |
There is a lot of concern recently over cat vaccines and rightfully so.
Unfortunately much of the reaction has lead to a lot of misinformation
and questions leading to many pet owners either not hearing about it,
having the information brushed over or avoiding vaccines which may be
necessary for their pet. I hope this lecture will have the following
effects: 1) hopefully convince people to never allow adjuvanted
vaccines given to their cat, 2) provide understanding on vaccine
related cancer and 3) provide links and information so cat owners can
make a vaccine choice that is right for them.
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| Adjuvants. What are they? |
An adjuvant is basically ‘something’ that makes vaccines work better. Adjuvants create tissue inflammation at the site of injection and thereby 'catch the attention' of the immune system to the vaccine. There have been two types of vaccines for a long time – live vaccines
and killed vaccines. Live vaccines utilize the live virus which has
been rendered ‘non virulent’ meaning that it does not create disease. A
killed vaccine utilizes a virus which has been killed and ‘chopped up’.
The advantage of a killed virus is that it is non possible for the
virus to turn back into an active disease causing virus but the
disadvantage is that they do not stimulate the immune system as well.
Thus adjuvants are needed to make killed vaccines work better.
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| How do adjuvants cause cancer? |
First of all, while there is a lot of supporting evidence or adjuvants
causing cancer along with an understanding of how they likely trigger
cancer formation, an absolute link has not been established. With the
presence of existing alternatives to adjuvanted vaccines, I do not see
any reason at this time for any cat to receive an adjuvanted vaccine.
So what is the theory behind the adjuvants? Well we know for a fact
that adjuvants cause chronic injection site inflammation. It is this
chronic inflammation which can act as a trigger for cancer growth. Some
adjuvants contain aluminum which will persist at the administration
site. One of the major concerns is also one of the reasons for some
lack of ‘definitive evidence’. This concern is that the time frame from
administration of an adjuvanted vaccine to cancer growth is 2 months to
10 years!
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| What type of cancer is it? How bad is it? |
Well cancer is never good, but fibrosarcoma, the most common vaccine
associated cancer, is particularly bad. If VAS is present then with a
combination of surgery, radiation therapy and chemotherapy, the
survival time is, on average 24-36 months. If only one of these options
is utilized, the a general estimation on life expectance is 6-12 months
post diagnosis. These figures are from Phil Bergman D.V.M.,
D.A.C.V.I.M. These are indeed scary figures for our pets. There are
also other tumors that are thought to be associated, although less
commonly than fibrosarcoma, with adjuvanted vaccines. They include:
malignant fibrous histiocytoma, osteosarcoma (bone cancer),
rhabdomyosarcoma (muscle tumor), liposarcoma (malignant fatty tumor),
chondrosarcoma (cartilage tumor), and undifferentiated sarcoma. All of
these are malignant and potentially fatal.
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| Should I still vaccinate my cat? |
In a word, yes. Vaccines save lives every day. I do a lot of rescue
work and cannot begin to adequately describe the suffering and death
seen in both dogs and cats which could have been so easily avoided with
vaccines. The good news is that with the recognition of this reaction,
there are two forms of vaccines which are NOT associated with this
cancer. The first is non adjuvanted modified live virus vaccines and
the second is recombinant vaccines. For the combination vaccine which
typically includes panleukopenia, rhinotracheitis and calici virus,
both of these forms exist. For feline leukemia and feline rabies, only
the recombinant vaccine exists. The non core vaccine FIV is only
available as adjuvanted. I will go over each vaccine briefly.
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This stands for Feline viral rhinotracheitis, calici and panleukopenia.
It is also known as a ‘combo shot’ or 3 in 1 vaccine, etc.. This
vaccine is available a modifiled live vaccine (MLV) non adjuvanted,
killed adjuvanted and killed non-adjuvanted. There is also a MLV non
adjuvanted intranasal form. The only form I recommend is a MLV
non-adjuvanted. It can be obtained through several manufacturers
including Pfizer and Merial. Both are fine however since the FeLV and
Rabies which is non-adjuvanted is ONLY available through Merial. It is
likely that the veterinary hospitals carrying three non-adjuvanted
vaccines will likely be using the same company.
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The FeLV (feline leukemia virus) and feline rabies vaccines by Merial utilize
recombinant technology. So what is Recombinant technology? It takes the
best of the killed virus vaccine and the live virus vaccine. Killed
vaccines take just the ‘bits’ of the virus that the immune system would
recognize and discard the rest of the virus. Recombinant vaccines take
a live harmless canary virus and places the antigenically recognizable
‘bits’ of the virus inside it. Thus it is a live virus which cannot
revert (unless you vaccinate a canary) and the selective properties of
the killed virus. No adjuvants are necessary due to the live quality of
the vaccine. Furthermore testing of the vaccines immunity have shown
excellent immune response and protection against challenge. Bottom line
– a technology breakthrough with the cats as the big winner!
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This vaccine is often avoided and skipped by concerned cat parents. For
those who should have this vaccine, please do NOT skip vaccination. The
non-adjuvanted vaccine is very safe and highly affective. This vaccine
has been known to cause more local inflammation than other vaccines so
was for awhile thought to be the only vaccine causing VAS. We know now
that this is not true. The nature of the vaccine does bring the concern
of inflammation. When Merial developed the recombinant FeLV vaccine
they found that the vaccine was still causing more than acceptable
inflammation. This inflammation was found to be from the pooling of the
vaccine under the skin. So Merial utilized a needless injector
developed by the military. The Vet Jet sprays the vaccine by a puff of
air under the skin which evenly distributes the vaccine. This
eliminates any pooling of the vaccine. So if the FeLV vaccine is
injected by a needle into your cat – it was NOT this vaccine. It can
only be given with the device. Let’s get back to the cats though. Do all cats need FeLV vaccine?
Yes and no. When they are a kitten, all cats should get this vaccine.
After the initial kitten set, it is generally recommended to have a booster. Thereafter, some clinicians recommend yearly vaccination for those cats who are known to be at risk. Some veterinarians will not recommend further vaccination. It is important to know that all cats, even those
never vaccinated, naturally develop some immunity against FeLV after a year
of age. So cats under a year of age, need protection. FeLV is a
terrible and inevitably fatal viral disease. We need to protect our
kittens from it. Cats over a year of age, should be vaccinated based
upon owner comfort and patient risk. I will have some more concrete
recommendations at the bottom.
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Not all states require rabies vaccination in cats. My state does not. I
still recommend this vaccine for most cats though. Rabies virus
infections do still happen here in the US and worldwide. If infected in
a human, it will, if not aggressively treated early, kill you. Since a
recombinant form of the vaccine is available for cats, then the benefit
versus risk is clearer. Whether you vaccinate your cat for rabies or
not though however is an individual choice. Some cats are very
sensitive to vaccines and live a pampered indoor low risk life style
and some cats spend some time outside in a high risk environment.
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Feline Immunodeficiency Virus (FIV) is analogous to HIV in humans. It
is another infectious virus with fatal implications. It is typically
transmitted by a bite wound. The vaccine – sounds great to have a
protection against AIDS right? Well not exactly. First of all it only
comes adjuvanted. That is problem one. There are more problems however.
There are five clades (basically strains) of FIV. The vaccine was only
designed to protect against clades A and D. When it was tested it only
was tested against clade A. For those in Canada, the FIV strain typical
to your area is clade C – which the virus was neither designed for nor
tested for. While the efficacy for clade A was not bad (82%), there are
four strains that we don’t know if the vaccine work at all for. Not
enough problems? How about this? Once vaccinated the cat will test
positive, sometimes forever and it is not possible on blood work to
adequately differentiate between vaccine induced positive and a true
positive. When I talked to the Forte Dodge representative in April
2007, their data revealed that at one year post vaccination 30% of cats
will test negative again but still be protected against challenge. No
other data existed at that time according to them. So what about the
other 70%? How long does it take for them to test negative? No way to
know according to the vaccine representative. This makes up for a lot
of concern about this vaccine. For this reason, many veterinarians do
not use this vaccine.
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Yes, there are more… but this lecture is on adjuvants. The links I provide at the bottom will go over those other vaccines.
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Dr Alice Wolf is a veterinary specialist who I have great respect for.
She currently is a consultant on our veterinary information network
(VIN) and a champion of non-adjuvant vaccine promotion. Here is her
response on vaccine protocols for cats:
“MODIFIED LIVE FVRCP starting at 6-8 weeks of age, give every 3-4 weeks out to 16 weeks.
Merial PureVax RV at 12 or 16 weeks (whatever is required for age in your area)
Merial PureVax FeLV at 8 and 12 weeks for ALL kittens
Year One: MLV FVRCP, PureVax RV, PureVax FeLV IF the cat is still at risk.
After that: MLV FVRCP every 3 years, PureVax RV yearly (until 3 year
approval is completed), then q3years, PureVax FeLV yearly if cat is
still at risk.
I give NO:
Chlamydophila
Bordetella
FIP
FIV
Virulent Calici
Alice”
-Alice M. Wolf, DVM, DACVIM, DABVP
Discussion date January 6, 2008.
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| What if my vet recommends something else? |
That is okay, as long as the vaccines are not adjuvanted. What if I
want to do a different plan? That is okay too. First each patient has a
different life style and demographic. Secondly the protocols are ever
changing .
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| Why don’t all veterinarians carry only non-adjuvanted cat vaccines? |
I don’t really know. One answer is price, they are more expensive. The
other is familiarity. Neither really makes sense. The price, while many
times that of cheaper options, is still only going to lead to a few
dollar increase in the owner’s cost. Also does price matter when we
compare the potentially cancer causing vaccine and the non cancer
causing vaccine??!
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| What if my vet does not carry this vaccine option? |
Well, for the vaccines at least, go somewhere else or try to convince
that vet to carry them, if she or he has that decision making ability.
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| Some additional resources: |
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| CLICK above for AAFP |
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| CLICK above for AAFP Vaccine Recommendations |
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| CLICK above for FeLV NonAdjuvant Information site |
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| CLICK above for Dr Brooks VAS Information |
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| CLICK above for VAS Task Force |
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There is still much information that is needed and this topic is ever
changing. For the time being, it is important that as we protect our
cats from infectious disease we do this as safely as possible. I hope
this lecture provides the information in a straight forward and useful
format. Again, if there are other topics that would be of interest or
if there are suggestions, please let me know. 
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