Cats: Vaccine-Related Sarcomas

This was a relatively short article and one topic, thankfully, that I have never experienced.  Since many of my cats do come from unknown backgrounds, I do suspect that some are at risk, but so far, so good. 

Recent Advances in the Treatment of Vaccine-Sarcomas, by Gregory K. Ogilvie, DVM
p 525-533 in Vol 31, No 3, Vet. Cl. of NA: Small Animal Practice, May 2001...

The article focuses on the diagnosis and treatment of the sarcoma and not on the fact that vaccines seem to cause sarcomas.  The latter is assumed by the article. The article doesn't mention, but from other sources the sarcomas are linked primarily to FeLV and rabies vaccines.

Physical exam -- The sarcoma appears as a lump or thickening either at the injection site or, interestingly, on the underside of the cat (migration of vaccine agent).  The lump can appear from days to years afterwards. This timing, days to years, is a bit scary since I do not know the vaccine history of many of my cats.

Evaluation -- The first step is a needle biopsy to confirm that it is a sarcoma.  The next step is xrays to determine if it has metastasized.  Enlarged lymph nodes may need to be biopsied.

Treatment of small tumors -- The recommendation is for a 2cm cuff around the tumor and 1 skin layer deeper.  2cm on both sides is HUGE!  The author mentions the inconclusiveness of both chemotherapy and radiation therapy, and from other sources, this does not seem to have changed significantly in recent years.

Treatment of large tumors -- The author recommends surgical reduction of the tumor followed by radiation treatment.

Metastatic sarcomas -- Chemotherapy seems to be the solution but at the time of writing there was no clear recommendations.

Patient Management -- The author stresses the need to give the client pain meds, anti-nausea meds, and appetite stimulants to help the cat.  Also, the client should be given written instructions and educational material because owners often are very upset when told their cat has cancer.

Prognosis -- For small, non-metastatic tumors, the prognosis is good.  Otherwise, the outcome is usually not good as the tumor recurs.  Who does the surgery and how extensive it was drastically influences the outcome:

"The median time of tumor control was 94 days.  Median tumor control for tumors treated with excision performed at a referral institution (274 days) was significantly longer than that for tumors excised by a referring veterinarian (66 days).  A radical first excision yielded significantly longer median tumor control (325 days) than did a marginal first excision (79 days)..... Few cats (13.8%) receiving only surgical treatment had long-term (>2 years) survival, suggesting that radiation and chemotherapy are highly indicated as adjunctive therapies."  And this is an interesting statement about radiation and chemotherapy given what the author said previously about the inconclusiveness.

These vaccine-related sarcomas are the reason the new vaccine protocols recommend vaccinating for rabies and FeLV in the legs or even tail -- those parts can be amputated to save the cat from the sarcoma.  To me this is very drastic and makes me ever so grateful that I don't have to vaccinate for rabies of FeLV.

Cats: Recommended Vaccines and Vaccination Schedule

This is a summary of the article:

Feline Vaccination Guidelines, by James Richards, DVM, and Ilona Rodan, DVM, p 455-472 

in Vol 31, No 3, May 2001, Veterinary Clinics of North America: Small Animal Practice

The development of the guidelines was based on the overall goals of vaccination.  These are “to vaccinate the largest possible number of individuals in the population at risk, vaccinate each individual no more frequently than necessary, and vaccinate only against infectious agents to which individuals have a realistic risk of exposure and subsequent development of disease.”  Kittens, which are more susceptible to severe infections, are the primary target and because of the maternal antibodies, they require a series of shots to develop proper immunization.

Use of polyvalent vaccines, that is, vaccines for more than one disease, is discouraged except for the 3 core vaccines (herpes, calici, and panleuk).

Feline Panleukopenia (FPV):  Because the virus can remain in the environment for over a year and because it has a high mortality rate in young cats, vaccination is recommended for all cats.  Maternal antibodies interfere with vaccination in kittens under 12 weeks.  Most vaccinated animals are 100% protected, although intranasal vaccines may not give complete protection. There are studies showing the duration of immunity (DOI) is at least 7 years. The vaccine for FPV does protect cats against canine parvovirus-2b, which can infect cats.  There are no associations with tumors.  Kittens and pregnant queens should not be vaccinated with modified live vaccines because of neurological development problems.

Feline Herpes (FHV-1) and Feline Calicivirus (FCV):  These two cause about 90% of respiratory problems in cats and are highly contagious.  Both are self-limiting in adults, but can be fatal in kittens.  Maternal antibodies interfere with vaccination in kittens under 12 weeks.  DOI is at least 3 years.  Vaccines reduce the severity of the disease, but do not prevent infection.  Topical vaccines (intranasal or conjunctival) are useful for cats placed in situations with ongoing URIs such as shelters and can be given to kittens as young as 10 days.  There are some reports of mild reactions, but no reports of sarcomas.

Rabies: Rabies vaccination is highly recommended for all cats and is required in some places.  The adjuvanted vaccine [adjuvanted means a vaccine with something added to increase the immune response] is associated with vaccine-reactions, such as swellings and with sarcomas.  When this was written, all rabies vaccines were adjuvanted, except for the recombinant form.

Feline Leukemia Virus (FeLV):  Vaccination should be based on age (cats under 4 months are most at risk) and risk of exposure (outdoors or mixed -/+ households are most at risk). Vaccination is NOT recommended for older (> 5 months) cats with little exposure [indoor older cats].  Different brands of vaccine vary in their immune response – separation of infected cats is a better alternative to vaccination.  The vaccines have been associated with fibrosarcomas.  DOI is about 1 year, requiring annual booster shots.

Chlamydiosis:  This bacteria causes conjunctivitis and respiratory problems, which respond well to antibiotics.  As with herpes and calici, the vaccine only lessens the effects, but unlike them, there are frequent reactions to the vaccine.  Because the reactions seem to outweigh the disease, vaccination is not recommended except where Chlamydia has been confirmed.

Feline Infectious Peritonitis (FIP):  The vaccine has two major problems.  First, the vaccine should not be given before 16 weeks of age, by which time most kittens are already infected with the coronavirus.  Second, “there is no evidence that the vaccine induces clinically relevant protection” – in basic, it doesn’t work.  Thus, it’s not recommended at all.

Dermatophytosis (Ringworm):  The vaccine does lessen the duration of ringworm infection and perhaps reduces the spores produced, but will not prevent infection.  DOI is unknown.

Bordetella bronchiseptica:  This causes respiratory problems, can occur into upto 80% of cats from shelters and multi-cat homes, and is self-limiting [cats routinely recover without medication].  At the time of writing [late 2000], there were no independent studies on this vaccine for either effectiveness or DOI.  It is only recommended for multiple cat environments like shelters, catteries, board facilities where Bordetella is known to exist.

Giardia:  This is a protozoan which can cause acute gastric upset.  The vaccine was not recommended for all cats as it was not proven effective in wide trials [as of 2000], but in licensing trials, the vaccine was shown to shorten the duration of diarrhea upon exposure and the length of cyst shedding.  It should be considered for cats in areas with giardia exposure.  DOI is 1 year or longer.

These guidelines were in 2001 very controversial as most vet schools were still teaching that vaccines had to be given annually to ensure immunity.  Likewise the comment that multiple vaccines should not be given at once, except for the main 3 core vaccines, which would eliminate 5-in-1 shots.

The actual vaccine schedule given in this article was later adopted by the American Association of Feline Practitioners and is given below.  Essentially, it is the same, only the timing of the kitten shots has changed and the deletion of vaccines which were deemed not necessary, such as ringworm.

Reading this article confirmed to me that my decisions regarding with respect to vaccinations are okay.  I say okay because I can see there may be a slight potential for improvement.  For most of my cats, I do not vaccinate at all.  They are older, come from shelters which always do the core vaccines on intake.  My cats are all indoors with no FeLV+ cats and no exposure to rabies.  So there's little reason to vaccinate them.

Bodhi, my kitten, may need a booster for the 3-in-1 core vaccines because he is a 'baby' and because he goes to cat shows.  Peaches I will have to think about since she goes to shows but she's older so I don't know.  It's the 'high exposure, stressful situation' in the comments that bother me because of the cat shows.  And Langston, who got his kitten shots at ~1.5 yrs, might benefit from a booster.

When NOT to Vaccinate

I've had several discussions in the last week about vaccinating cats.  I've been surprised by some of the comments by people who really should know better.  (And I will ignore the "it's unethical not to vaccinate" comments until another time.)

Let's assume you are going to vaccinate your cat.  Your cat, your decision.  There are some clear and (I thought) obvious times/situations when you should not vaccinate:

• If the cat is sick with say an URI or even UTI.  Vaccines may be ineffective when a cat is sick because the immune system is already taxed to overcome the illness.  Almost all vaccines say to vaccinate only healthy cats.

• Right after a cat has been sick.  Yes, the cat is over the URI and shows no symptoms.  This does not mean the immune system is back to normal.  It takes 2-6 weeks for the immune system to return to normal, depending on the illness.

• When dealing with any immune system problems.  (This will raise some eye brows.)  Vaccines stimulate the immune system.  If a cat has, for example, IBD or even severe allergies, both immune related disorders, the vaccines can trigger an increase in the immune-related problem.  

• Cats over 12 years old.  Most older cats have a decreased immune system to begin with.  By forcing the immune system to deal with 3-4 major diseases (which is what a vaccine really does), can easily overwhelm the immune system and lead to major problems.

• When the cat is being spayed, neutered, etc.  The cat's immune system will work at preventing a bigger problem (infection) and may not adequately respond to the vaccine.

• After a cat has had a severe reaction.  If the cat was vomiting and listless last year with the vaccine, it's really not going to better this year.

• Very young kittens.  The mother cat's milk has antibodies in it so the young kitten has her immunities.  Once the kitten is weaned, the antibodies fail. Depending on the kitten, the immunity from the mother can last 6-12 weeks.  Vaccinating early during this time can be ineffective at best, and according so some researchers, can impair the immune system for the life of the animal.  (The immune system is not fully developed until around 5-6 months.)  The best option would be to have titers done to assess antibodies, but few vets know how to do this.

• When the cat was vaccinated for it last year.  Even the AVMA now recommends every 3 years on most vaccines.  Some researchers have shown vaccines can easily last 8-10 years!  So, subjecting a cat to repeated vaccines does nothing to strengthen immunity, but may instead lead to weakening and overwhelming the immune system. 

Personally, I don't vaccine my cats.  Many of my cats have been vaccinated because the shelters I adopted them from did it and would not release the cat without the vaccinations.  But I have always associated certain problems with these vaccinations.  For example, Clarissa was vaccinated with a 4-in-1 shot about 3 days after finishing her antibiotics for an URI and at the same time she was spayed.  Talk about hitting her immune system hard!!!  She did have a reaction to the internal stitches.  She has a reaction to raw meat.  She has a reaction to cooked fish.  How much of her food allergies are related to her vaccinations?  I can't prove causation, but my gut instinct says they are related.

Now, I know all this goes against what most vets say.  So why do vets not follow these guidelines?  There are many reasons.  Most vets believe the idea that vaccines are safe and effective, with little side-effects.  Selling vaccines is a major source of income in many vet practices.  Some vets have never thought about how vaccines work and their effect on the immune system since they were in vet school.

While I understand I am in the minority when it comes to vaccinations, I would just like people to take a few minutes and think before they have their cat vaccinated.