1401 W. Webster Ave., Chicago, IL 60614

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For the past 15 years, during all feline annual examinations, we have discussed Vaccination Associated Sarcomas (also called Injection Site Sarcomas) and our attempts to reduce their incidence. Since the emergence of these tumors, vaccination studies have been ongoing and recommendations continue to change. We want to ensure that all of our cat owners understand the most recent recommendations.

The facts:

  1. One to three tumors per 10,000 vaccines administered will affect our feline patients. Usually a Rabies or Feline Leukemia vaccine, containing an aluminum adjuvant, will stimulate a malignant tumor called a fibrosarcoma right at the injection site. It starts as a small lump, called a granuloma. Depending on the cat’s immune system, the lump may disappear within three to four weeks, or it may continue to increase in size, transforming into a malignant fibrosarcoma. Once the tumor forms, it is extremely aggressive locally and very difficult to completely surgically remove. Multiple types of chemotherapy, as well as radiation therapy, have been tried post-surgically to prevent recurrence, with variable success.
  2. IT IS REQUIRED BY LAW, as well as an important preventative measure, to continue to vaccinate against the Rabies virus. Not only is Rabies fatal to cats, it is fatal to humans and readily contagious through exposure to infected saliva. Multiple occurrences of bats getting into people’s homes and high-rise apartments are reported yearly in Chicago. The state of Illinois may elect to quarantine an unvaccinated cat for up to six months if exposed to a bat.
  3. Keeping the above information in mind, we feel uncomfortable discontinuing any Rabies inoculation, even in strictly indoor cats. Since May 11, 1999, Family Pet Animal Hospital has been using, exclusively, the Purevax Rabies Vaccine (manufactured by Merial) for cats. It is the only rabies vaccine made that does NOT have adjuvants or liquid fillers, so it virtually eliminates injection site inflammation that could lead to a vaccine sarcoma. It is still licensed for only a one year duration, although it may be just a matter of time before a longer duration approval will be achieved. Researchers on the Vaccine Sarcoma Task Force have proven this to be the safest Rabies vaccine available.
  4. All Feline Leukemia vaccines should be discontinued unless there is absolute concern that your cat may be directly exposed to another cat, especially a stray. This includes indoor-outdoor cats, as well as cats that live in garden-level apartments and spend time in ground-floor windows with screens that may allow saliva from a stray cat to pass through. When this vaccine is necessary, it is a yearly vaccine after the initial two boosters.
  5. The FVRCP vaccine, protecting against Distemper and upper respiratory viruses, is a three-year vaccine at Family Pet (as recommended by the American Association of Feline Practitioners.)The vaccine we use is a modified live virus (MLV) vaccine that has no adjuvant and therefore little chance of causing inflammation and subsequent Vaccination Associated Sarcomas.
  6. The Rabies vaccine should be injected subcutaneously as low as possible in the right hindlimb and the Feline Leukemia vaccine (if absolutely necessary) should be given similarly but in the left hindlimb. The FVRCP vaccine should be placed as low as possible on the right shoulder. The thought behind this protocol is that if a tumor should develop it will be easier to treat surgically when located on a limb than in the shoulder-blade area. In addition, all of our vaccines are given from single-dose vials instead of ten-dose tanks, to eliminate the risk of adjuvant settling to the bottom of the vial and having a higher concentration in the last two to three doses.
  7. To monitor your cat, run your hands over the area(s) where the vaccine(s) were given. Check weekly for lumps (a hard, knot-like structure) in or just under the skin. Generally, lumps are firm and not easily missed. They will usually be nonpainful and about the size of a marble when first discovered. A lump may form YEARS after vaccination, and any lump found should be examined ASAP. Local lumps that develop at the site of the vaccine usually resolve without treatment in 2-4 weeks. Those that persist longer than 6 weeks should be biopsied. These masses are always biopsied prior to surgical removal.
  8. A vaccination titer refers to a blood test that measures antibody protection produced in response to the last vaccine given. In other words, does your pet still have protection from the last vaccination given? Does s/he really need this vaccine? These titers are easy to obtain with a blood sample, and are reasonably priced. Currently we are recommending measuring vaccine titers instead of automatically vaccinating any patient with a chronic illness, history of previous vaccine reactions, or immune disorder, as well as our geriatric patients. If the titer comes back “protective”, then the patient does not need the vaccine this year and the titer should be rechecked in one year. If the titer is not “protective”, giving the vaccine may be recommended, depending on the patient’s health and the risk factors as discussed with your veterinarian. The exception to this is the Rabies vaccine; this vaccination is regulated by law in our state, and the choice whether or not to give it is out of our hands.
  9. Be assured that the doctors at Family Pet Animal Hospital will keep apprised of all changes in vaccinations and Vaccination Associated Sarcoma treatment based on ongoing research by our universities. Our mission at Family Pet Animal Hospital has always been and will always be your pet’s health. Due to vaccinations, we rarely see Feline Panleukopenia or Rabies and have seen a great reduction in cats with Feline Leukemia Virus. We have worked hard to update our facility on an ongoing basis to provide state of the art diagnostics and treatment modalities. Yet there is nothing that replaces a physical examination for early detection of problems prior to our pets displaying signs of illness. We strongly encourage all of our clients to continue to make a yearly or twice-yearly examination appointment; a time to check all systems and educate you on the most current thoughts in our field that may be life-saving for your pet. Please call our office if you have any questions concerning this information.
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