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    Indoor Cat Only Needs Rabies Shots Yearly (?)
    An_249731 posted:
    I have 2 dogs (7 year-old terrier mix and 4 year-old Australian shepherd mix) and 1 indoor cat. The dogs interact with different types of dogs all the time (dog parks, trekking, etc.) so my vet told me that the best way to protect them is through Trifexis. My cat, since he interacts with the dogs, is being protected by Revolution. I read that vaccines are not necessary for indoor cats, should I just give him his rabies shot yearly and not bother with the others? He never goes outside except for the garage where insects can get in.
    Drew Weigner, DVM, ABVP responded:
    That's a discussion to have with your veterinarian, who knows your cat and your situation. In most areas, Rabies vaccinations are required by law, but other vaccinations are not. The American Association of Feline Practitioners has published Vaccination Guidelines for many years that are highly regarded. You can read them at:

    Drew Weigner, DVM, ABVP
    The Cat Doctor
    Board Certified in Feline Practice
    Kristi1223 responded:
    The vet we go to offers a 3 year rabies vaccine for felines, so I only have to haul mine in every three years for their rabies! They have also started offering the other vaccines that last 3 years, it's great!
    srstephanie replied to Kristi1223's response:
    Hi Kristi,

    Unfortunately, the choice of rabies vaccine for cats isn't that easy ... at least for now.

    For cats there are two types of rabies vaccines:
    1. Killed Virus (also called "inactivated")
    2. Recombinant

    The problem that comes up with feline vaccines is that some cats develop a very aggressive type of cancer at the vaccination site ... called a fibrosarcoma. They have been called more specifically "Vaccine Associated Sarcomas" (VAS) but the experts seem to be changing the terminology to "Feline Injection Site Sarcoma" (FISS) since they "can" develop after other types of injections as well.

    Research has shown that the problem revolves around how the cat's immune system responds to chronic inflammation. What happens is that a mutation occurs to the "p53 gene". The p53 gene is a tumor suppressor gene. When it mutates, it allows tumor growth, i.e. a fibrosarcoma (and occasionally other types of cancer).

    The two elements required for a VAS/FISS to develop are:
    1. inflammation (particularly chronic inflammation)
    2. a genetic predisposition that results in a mutation to the p53 gene in the inflammation

    How does this effect vaccination choice?

    Killed Virus (inactivated) vaccines are made using a dead virus (e.g. dead rabies). But the immune system knows that something dead is not a threat. So, in order to get the immune system to respond, they MUST use a chemical additive, often aluminum, called an "adjuvant". The whole purpose of an adjuvant is to hold the vaccine at the vaccination site and create INFLAMMATION ... and studies have shown that it is a chronic inflammation that can last months (and likely years).

    The other option for rabies vaccines for cats (not for dogs) is the recombinant rabies vaccine (designated as "rRabies"). A recombinant vaccine is made by taking ONLY the small piece of DNA (not the entire virus ... so rabies is not present in the vaccine) that is needed to produce a protein that triggers the immune system to develop antibodies that will protect the cat from rabies. Injecting just that piece of DNA won't work ... so the DNA is inserted (i.e. "recombined" ... hence "recombinant" vaccines) with a carrier virus (known as a "vector"). For the feline rRabies vaccine, the small piece of rabies DNA is inserted into the Canarypox vaccine (vector). Canarypox is a bird virus and cannot reproduce in mammals, so there is no danger of giving a cat "canarypox" disease. But when it tries to replicate, the canarypox breaks apart and delivers that piece of rabies DNA which produces immunity to rabies. It is a very good vaccine that gives very good protection.

    What is important, is that the recombinant rabies vaccine does NOT contain any adjuvant and produces very little inflammation that only lasts a couple days.

    A recently published statistical study by Dr Phil Kass of UC Davis (who is highly respected) concluded that cats given a recombinant vaccine have a significantly lesser risk of developing a VAS than cats given a Killed Virus rabies vaccine.

    Okay, back to the issue of using a 3 year rabies vaccine. ALL licensed 3-year rabies vaccines are ADJUVANTED Killed Virus vaccines ... which increase the risk of a VAS.

    The recombinant rabies vaccine is only licensed for 1 year (must be boostered annually) but has NO ADJUVANT and reduces the risk of a VAS.

    So here is the dilemma ... vaccinate only every 3 years but use an adjuvanted KV vaccine that increases the risk of an aggressive and lethal cancer.

    Or, use a recombinant vaccine that must be boostered every year, but reduces the risk of cancer.

    Every vet school in the US and the majority of vaccine experts choose to use only non-adjuvanted vaccines (i.e. they only use the rRabies).

    The frustrating thing is that there is a new study in Europe by Merial (which makes the only rRabies vaccine) that shows it protects for at least 3 years ... but it is only licensed in the US for 1 year. Thus the dilemma.

    Hope that helps,
    Stephanie in Montreal
    srstephanie replied to srstephanie's response:
    Hi Kristi,

    Sorry, I know I get wordy when trying to share info ... and wanted to just add a little more info for you.

    First, I need to let you know that I'm not a vet and have no credentials. But my "hobby" is listening to talks given at vet CE conferences by some of the top experts. Over the past 5 years, I've become friends with Dr Richard Ford, now emeritus at NC State (ranked the 3rd best vet school in the US) who has also become my mentor and feels I have a good grasp of vaccine issues. Dr Ford is an Infectious Disease expert and known internationally as a guru of vaccines and vaccination protocols. He is a co-author of both the official 2011 AAHA Canine Vaccination Guidelines and the AAFP Feline Vaccination Guidelines (just updated and due to be published at any time now ... he also helped write the previous version in 2006). So, all that is to say, I'm not a vet but I am trying to share info from one of the top experts on feline (and canine) vaccinations.

    Dr Ford and most of the experts feels VERY strongly that cats should never receive adjuvanted vaccines (i.e. never receive killed virus/inactivated vaccines).

    That said, there are also a couple specialists who disagree ... such as Dr Mike Lappin of Colorado State and Dr Gary Norsworthy, a feline specialist in Texas. They put the emphasis on the genetic component and say that if a cat has the genetic susceptibility, it can form a VAS after ANY injection ... and actually anything that causes inflammation.

    While they are correct that some cats develop a sarcoma from any type of inflammation ... the fact is that adjuvants used in KV vaccines are intended to cause chronic inflammation. Cats have received injections for many years. But it was only after KV vaccines for rabies and FeLV began to be used in the mid 1980s that vets suddenly saw a major increase in the cases of VAS in cats.

    Cats can also develop a Vaccine Associated Sarcoma up to 9 years after the last vaccination. So, just because a cat doesn't develop one immediately after a KV vaccine, it could do so years later.

    On the other hand, VAS is still relatively rare ... with estimates of anywhere from 1 in 1,000 vaccinations to 1 in 10,000 vaccinations. But if it is your cat, that's still too many.

    The AVMA formed a VAS Task Force in the 1990s. All they could do (since recombinant vaccines didn't exist at the time) was to suggest sites for vaccinations ... which were:

    -- Rabies in the Right hind leg
    -- FeLV in the left hind leg

    Both as low on the leg as possible (below the knee).

    Why? So that if a cancer develops, one can cut off their leg and try to save their life. Dr Ford's point is that is not something we should settle for. Why use an adjuvanted KV vaccine and give it where you can cut off their leg if they develop cancer? Why not use a less inflammatory vaccine (i.e. recombinant) and reduce the risk of a sarcoma?

    The AVMA VAS Task Force also came up with a 1-2-3 Rule to help determine when to biopsy a lump at the vaccination site:

    biopsy any lump that is ...
    1. still growing after 1 month
    2. more than 2 cm in size
    3. still exists after 3 months

    So, this is the choice every pet owner has to make ... and should discuss with their vet. I also have a cat that HATES going to the vet. But I also choose to use an annual vaccine that is not adjuanted (the recombinant rabies) rather than a 3-yr vaccine that is adjuvanted.

    As for the other core vaccines (herpes, calici, panleukopenia) all modified live vaccines for them are good for AT LEAST 3 years and likely longer. After the first adult booster, the panleukopenia portion is thought to be protective FOR LIFE (though they still recommend boosters every 3 years).

    Most of the non-core vaccines do require annual boosters (e.g. chlamydophila, bordetella, FIV, FeLV). Use of them depends on risk of exposure that your vet can discuss with you.

    Hope this gives you (or others) something to think about and discuss with your vet.

    Stephanie in Montreal

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