Tuesday, February 22, 2011

Dangers of Vaccines


You're supposed to get your cat vaccinated every year, right? Well, maybe not for everything.

In a presentation yesterday at the Western Veterinary Conference entitled "Feline Vaccination: Protocols, Products and Problems," Dr. Alice Wolf of Texas A&M University outlined concerns about the safety of some vaccines for annual use on cats.

You see, vaccines work by introducing either the dead or a modified live version of the disease-causing agent into the cat's bloodstream. The body then produces antibodies that kill the invading pathogen, producing immunity from the disease in the cat. But about 20-25 years ago, some modified-live versions of rabies vaccine resulted in the animals actually getting rabies. Yes, from the vaccines. The veterinary community began using new types of vaccines made with killed rabies virus. To improve their effectiveness, the vaccines were "adjuvanted", or enhanced with a substance containing aluminum. This increased the body's immune response to the invading virus and improved the effectiveness of the vaccines, without the risk of actually causing the cat to get rabies. Another advantage was that the cats only needed to get these new vaccines every three years instead of annually. Hmm, more efficient and saves you money! Great improvement, right?

Well, not so fast! Dr. Wolf explained that these adjuvanted vaccines are now being shown to cause vaccine-associated sarcomas (VAS), a type of cancer, in cats. The substance used to create adjuvanted vaccines is deemed by the World Health Organization to be a Class 3 carcinogen, with Class 4 being the strongest. Up to 20,000 cats per year have shown symptoms of VAS.

What does Dr. Wolf recommend? Citing a study by Dr. Julie Levy of the University of Florida, she noted that the modified live virus (MLV) vaccines are much more effective than the killed-virus versions. They provide quicker protection and work on a wider number of animals. She highly advised fellow veterinarians to opt for the MLV versions given annually.

But what about other diseases beyond rabies? Dr. Wolf said that only the FVRCP vaccine that protects against feline viral rhinotracheitis, calicivirus, and panleukopenia, needs to be given at all. Others are ineffective and expose your cat to unnecessary risks. Kittens should also receive the FeLV, or feline leukemia, vaccine because they are at higher risk for that disease, as should older cats that go outside a lot. But most adult cats have a higher natural immunity to FeLV and if they stay indoors, it is not a major risk for them.

There are also vaccines Dr. Wolf does not recommend be given to cats at all. They are:
  • giardia
  • feline infectious peritonitis (FIP)
  • feline immunodeficiency virus (FIV)
  • virulent calcivirus
  • bordetella
In addition to their being ineffective, they are not needed. She said that a vet practicing good hygiene and disinfection procedures and isolating sick or shelter cats from regular patients should have no problems with spreading contagious diseases between patients.

As a responsible cat owner, be aware of what's being used on your cat, and ask your veterinarian to use the safer options whenever possible.

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