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: Adverse Reactions to Vaccines

One of the major objections to vaccines by many people who do not vaccinate their cats has to do with reactions to the vaccines.  I know from personal experience with my cats that most cats have little reaction to vaccines, but for others, the reactions can linger for 3-5 days, cause vomiting, and cause stiffness.  I have also heard of much stronger reactions, to the point of death.  (I also acknowledge that some of the reactions may be overstated by upset owners, but still....)

This article, Vaccine-Associated Adverse Events, by E. Kathryn Meyer, VDM (p 493-514 in Vol 31, No 3, Vet. Cl. of NA: Small Animal Practice, May 2001) was interesting for several reasons.  First because it explained how the reactions are noted in the licensing of vaccines.  And second because of the range of reactions which the author admits to.  This latter is especially interesting because in personal conversations with various vets, I have been clearly told that there are none or almost no reactions to vaccines.

General Background on How Vaccine Reactions are Studied

Prelicense Studies:  These are trials conducted by the vaccine manufacturer, involving a small number of animals.  With cats and Chlamydia for example, there are 20 vaccinated cats and 10 control cats.  To get a label claiming prevention, the vaccine must be 80% effective.  Each vaccine batch must be in vitro tested for potency. 

The duration of immunity (DOI) determines the revaccination interval, but DOI studies are not required to support vaccine label recommendations for boosters.  This seems a bit inconsistent to recommend boosters without any evidence that boosters are needed.

The safety of a vaccine is determined by a larger field trial, which may or may not capture adverse reactions which are rare.  If there are adverse reactions observed, these are NOT required by law to be on the vaccine label.

Postlicense Studies:  “systematic monitoring of canine and feline infectious disease, with the exception of rabies, is not routinely performed”.  So, in essence, one cannot say that statistically the use of the herpes vaccine has decreased the incidence of the disease, although common observation would say it does. 

Reactions after licensing also do not have to appear on the vaccine label (except in certain specific cases with dog vaccines) and manufacturers are leery of doing so because it creates the image that their vaccine is unsafe.  The postmarketing surveillance is mainly by passive systems in that the vet contacts both the manufacturer and the USDA, but the few vets do this and in most cases (97%) they will report problems only to the manufacturer.  In 2001, the USDA Center for Veterinary Medicine was going to publish a rule requiring industry reporting of adverse reactions.  It does not seem this rule was ever published because (a) I could find no reference to this rule in vaccine discussions after 2001 and (b) as late as last year, reporting of vaccine reactions still was on a voluntary basis by the individual vet.

Adverse Reactions

Systemic Reactions: Nonspecific Systemic Reactions
This is anorexia, lethargy, fever, and soreness from 1-36 hrs after inoculation.  Most cases are mild, but a few are severe, and are presumed to be an immune response to the vaccine.  In a clinical study, the rate was 1.2% with cats older than 1 year and cats receiving multiple vaccines at greater risk.  The implications of this seem to be that a previous vaccination as a kitten may very well prime the immune system to react to the vaccine.  Also, this seems to be in alignment with many holistic vets' recommendation not to give multiple vaccines at one time.  For example, vaccinate for FeLV one month and rabies the next month, instead of all at once.

Systemic Reactions: Anaphylaxis
This is a reaction involving the lymph system (IgE mediated) involving the skin, intestines, and lungs.  The reaction can last up to 48 hrs and may require steroids, antihistamines or epinephrine.  In a study, 0.26% of cats had an anaylaxic reaction with 66% of those involving the intestinal tract, 22% respiratory, and 12% skin.

Systemic Reactions: Autoimmune Disease
Interesting, there are no reports of vaccines triggering an autoimmune disease in cats, only in dogs.  The time frame was 2-14 days and involved problems like hemolytic anemia.  My personal, non-vet opinion, is that some of the autoimmune diseases, such as IBD, are actually triggered by over-vaccination, but as the author clearly stated, there is no evidence for this view.  Then again, proving causation between a vaccine and a long-term immune problem would be difficult at best.

Systemic Reactions:  Immunosuppression
One study showed that some kittens vaccinated with an intranasal modified live panleukemia vaccine became immunosuppressed which lead to a systematic infection by Salmonella. When I think about this, this is not surprising since a vaccine works by challenging the immune system.  If the immune system is working to fight off panleuk then other bacteria and viruses can easily be overlooked by the immune system.

Systemic Reactions:  Vaccine Virulence
Modified-live vaccines (MLV) can cause reactions similar to the disease.  Calici and herpes MLV are well known to cause sneezing and sniffles 4-9 days after proper vaccination.  Calici MLV can cause ‘limping calici’.  With pregnant cats, MLV can cause fetal abortion or developmental problems. There are reports of MLV for rabies not being inactivated enough that it actually causes rabies.

Systemic Reactions: Product Contamination
Each batch of vaccine is tested for other viruses, fungi, mycoplasma, and bacteria.  Vaccine contamination still does occur and when it does, it affects a large number of animals.  But there are no specific statistics on how wide-spread the problem is.

Local Vaccine Reactions:  Pain
In cats, lameness lasting for a few days to several weeks is not uncommon since vets are now vaccinating in the hind limbs.  The lameness is from an inflammatory response.

Local Vaccine Reactions:  Benign Swellings
These swellings are not considered an adverse reaction by many vets, but the normal reaction.  Rabies vaccines in cats accounted for 72% of reported ‘benign vaccine lumps’.  In a small study of 9 cats, all cats developed them after rabies, only 1 after FVRCP, and none after FeLV.

Local Vaccine Reactions:  Injection Site Sarcomas
This was a topic of a separate article and will be dealt with there.

Local Vaccine Reactions:  Vaccine Site Alopecia
Most reports of hairloss at the injection site are related to rabies vaccine.

Local Vaccine Reactions:  Abscesses
With cats, the reports were linked to ringworm vaccinations.  As a side-note, the ringworm vaccine was never common and now seems to be unavailable in the US.

Local Vaccine Reactions:  Intranasals
Problems involving the FVRCP vaccine include nasal ulcers, oral ulcers, and eye ulcers.

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.

This Blog, Facebook, and a New Direction

For some time, I've been wondering what to do with this blog as I don't want to delete it but I don't have time to do a lot of writing for it either.  My Facebook group, Feline Health Research Group, seems to have taken most of my free time between answering questions and reading articles to summarize.  The big problem with Facebook, other than the personal threats, is that searching on there is a joke.  This blog, however, is indexed by Google and is very searchable....

So, I'm going to transfer some of the summaries of articles I wrote for the FHRG to this blog. Not only will the information eventually be searchable, but I can change types, add photos, add links, etc.  I can also do a bit more digging on some topics and add more to the articles, usually newer information.