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Feline Vaccination Associated Cancer - What You Can Do To Prevent It


Fibrosarcomas (VAS)

A.K.A. Feline post-vaccinal sarcomas or FISS

Read About A New 2015 Treatment Option For Your Cat here

Besides only vaccinating your cat when it is really necessary, the best way to give your vet safer option in treating this problem if it occurs is probably to ask that the vaccines be given in its tail. Read about that here. See how its done here.

In 2013, two articles by British veterinarians summed up current thinking about this unfortunate problem. First, injection of just about anything and everything will, (on rare occasion only) cause these tumors to form and, no injectable vaccine is entirely free from the problem.  So the official name has been changed to Feline Injection Site –Associated Sarcomas (FISS).



Other Entrées With The Same Flavor :

A Science-Based Pet Vaccination Program

Autoimmunity and vaccines


Second, the best prevention is to not give your cat unnecessary or too frequently-administered vaccines.

Beware the postman’s delivery of yearly pet vaccination "reminders” or the appearance of the “vaccination bus” at your local supermarket or pet megastore.

Giving your cat vaccines is not the same as paying your yearly tax assessments.

Apparently, massaging the point of vaccination was not the reason I never saw these reactions in my clients cats. Read more about those

vet’s opinions here and here, but be forewarned in the first one of some graphic photos.

Ron Hines DVM Ph.D

Lots of my articles are plagiarized and altered on the web to market products and services. There are never ads running or anything for sale with my real articles. Try to stay with the ones that begin with http://www.2ndchance.info/ in the URL box or find all my articles at ACC.htm.

We all know that older cats like older people are more susceptible to cancer. But in the late 1980’s, veterinarians began to see a strange tumor occurring on the body of cats at much too young an age. Pathologists, examining these tumors, found that most were highly malignant tumors of the connective tissue of the body called fibrosarcomas. They were named feline vaccination-related fibrosarcomas or VAS for short.

Both sexes of cats and all breeds seemed equally susceptible to VAS. These tumors began to develop as early as a few weeks after a vaccination or not for many years. They spread slowly and could usually be removed - but they had a nasty tendency to come back. Usually, they return in the same general area where they were removed, but a few cases moved to other locations in the body.

The original outbreaks were along the North Atlantic coast of the United States. Several astute veterinary pathologists who were sent samples from these patients noticed that the tumors were occurring in areas of the body where cats received their vaccinations.

We think that approximately one to ten in 10,000 cats developed these post-vaccination tumors. Several years before the tumor’s appearance on the East Coast, there had been an outbreak of rabies in raccoons in the area as well as an increase in feline leukemia cases. These two outbreaks caused more cats than usual to receive annual booster vaccinations. This was also a time shortly after the U.S. Food and Drug Administration began requiring certain aluminum-containing additives called adjuvants to be added to the vaccines to increase their potency. We became suspicious that the adjuvants were a part of the problem.

However, something else was happening in North America that we still do not understand. We still see VAS occurring more frequently in cluster areas. We all use the same vaccines and supplies - so how can this be? Perhaps veterinarians in different areas give vaccinations differently because they were taught to do so in regional veterinary schools. Perhaps the genetics of cats differ from area to area or some factor in the environment is partially responsible. No one knows for sure.

Ninety Nine percent of cats do not develop post-vaccination tumors.

For The Ones That Do Develop Tumors:

Cats are unique in their high susceptibility to tumors at vaccine injection sites. However, we have noticed that some cats develop inflammations identical to those that precede tumors when antibiotics or even sterile water are injected under their skin. One theory about cat fibrosarcomas is that hair is carried in with the injection causing an inflammation that can lead to tumors. Another is that cats that develop sarcoma tumors have a gene that makes them more susceptible to this form of cancer. As the theory goes, this gene remains “off” through most of the cat’s life and usually causes no problems. However, the gene can be turned “on” by inflammation or infections under the skin. So anything that causes an inflammation, could turn on that gene causing a sarcoma to form. No one knows for sure.

What Do These Tumors Look Like?

When a cat is developing a vaccination-related fibrosarcoma, owners notice a small lump when they are petting or grooming their cat. These lumps are usually about a centimeters or two in diameter and a bit flattened by the time they are noticed under the pet's skin.

Normally, skin tumors of this size can be easily removed surgically. The problem with this particular type of tumor is that cancerous cells extend invisibly outward into what appears to be healthy skin , and muscle.

What to Do If You Find A Lump on Your Cat:

First of all, remember that most vaccine reactions are not cancerous and disappear within a few weeks of vaccination. If you notice a small lump at the site of vaccination that persists more than a week call the veterinarian who administered the vaccinations and have him or her re-examine the cat. Most veterinarians are more than happy to do this. Generally, their advice will be to wait a little longer for the swelling to go away.

We wait because a small percentage of cats, develop transient a post-vaccination inflammation. These reactions are usually sterile abscesses caused by irritation and inflammation due to some of the vaccine components. These reactions occur 7 – 12 days after a vaccine is given, and also feel like small, firm lumps under the skin. They seem to go away without any lasting effect.

Things You And Your Veterinarian Can Do To Prevent Fibrosarcoma:

1) Give no more vaccinations than are required. We tend to vaccinate cats too often. Adult cats do not require yearly vaccinations other than rabies. When you do take your cat in for rabies vaccinations, request a recombinant rather than an inactivated vaccine. These more advanced formulations appear to be less likely to cause injection-site sarcomas. (ref)

2) Give booster vaccinations only when your cat's immunity is low. The cat's level of immunity and need for booster vaccinations can be determined by running blood titers .

2) Use only three-year, non-adjuvented vaccines in your cats. Adjuvented vaccines give us longer terms of immunity but they also cause considerably more local tissue inflammation than non-adjuvanted vaccines. Vaccine manufacturers are quickly shifting to vaccines that do not contain irritating enhancing chemicals. We think that these new vaccines will be less likely to cause tumors. Whenever possible, use an intra-nasal vaccine or one that requires no injection .

3) Request that your veterinarian use 25 gauge needles when administering vaccines to your cat. Small hypodermic needles are less likely to carry irritating hair and debris under the skin.

4) Request that your veterinarian massage the area where the vaccine was administered. Massage spreads out the antigen (vaccine) lessening inflammation.

5) Veterinarians that see many cases of VAS sometimes begin giving their vaccinations in a lower rear leg. Although the plan is somewhat gruesome they realize that a tumor occurring on the leg would allow the leg to be lost but the cat to be saved.

6) Be sure your veterinarian keeps accurate records of the brand of vaccine used and the site where it was given. Although this may not help your pet, it will help us to determine which brands of vaccine may be causing problems. To identify the vaccine used, it is now recommend that the feline panleukopenia-calicivirus-chlamydia-rhinotracheitis vaccination be given on the right shoulder. Rabies vaccination should be given on the right rear leg as far down the leg as possible. Feline leukemia vaccination should be given on the same spot on the left rear leg

7) Many medications (such as corticosteroids, antibiotics, etc.) can be given in pill form rather than by injection. The medication in most tablets will be in your cat's blood stream in less than an hour. So unless there is a pressing need for immediate action, avoid as many injections as you can for your cat. I know that cats are hard to pill - but the same study I referred to above (ref) appeared to find a relationship between non-vaccine injections and the formation of fibroscarcomas.

What Can Be Done If My Cat Develops A Fibrosarcoma?

Unfortunately, even with aggressive surgery alone, relatively few cats with VAS are cured. This is because the tumor is like an octopus - it has unseen tentacles that reach out far from the visible tumor.

This means that the first attempt to remove this tumor has to be radical, major surgery. Your chances of curing your pet are greatest if this is done by a veterinary surgeon who specializes in removal of feline fibrosarcomas. Combining this aggressive surgery with radiation therapy increases your cat's chance for survival. So far, chemotherapy has not been as effective as radiation.

If you can afford it, have your veterinarian make contact with a major veterinary center where a specialist is located . This should be done as soon as the diagnosis is confirmed through biopsy, to give your pet the greatest chance for survival. If you can not afford that approach, find a local veterinarian who is up-to-date on this type of surgery because if the tumor is removed similarly to how other superficial tumors are removed, it will undoubtedly reoccur quickly.

How veterinarians immunize cats, how vaccines are manufactured and how and how often we give them are all changing rapidly because of these fibrosarcomas. It appears that we are making progress because the disease seems to be shifting to older pets - pets that probably received the causal vaccination many years ago. But because we can evaluate these changes only in hind sight, it will be several more years before we know which changes have helped your pet.