BY DR. TRACY ACOSTA
Vaccinations for pets remain one of the cornerstones of preventative veterinary medicine today; however, around 1991 veterinarians started to notice a higher than expected number of injection site sarcomas (tumors) in vaccinations to cats.
A sarcoma is a malignant tumor that can develop and spread quickly. Even after surgical removal, recurrence is a common complication.
In response to this problem, veterinarians, researchers and manufacturers have explored the reasons why this happens in anywhere from 1 in 1,000 to 1 in 10,000 cats that receive an injection. It is important to note that initially only vaccines were implicated as causing the sarcomas. Now it has been shown that any type of injection can result in an injection site sarcoma in cats.
Research has demonstrated that these sarcomas are the  result of an exaggerated response by the cats' immune systems. Besides the inflammatory response that can be caused by an injection, the use of adjuvants was also noted as a possible cause of the sarcomas. Adjuvants are chemicals that enhance an animal's immune system response. So, recently the concern has been focused on the two major potential risks involved with vaccines: injection site inflammation and the use of adjuvants.
The newest feline leukemia vaccine promises to offer much hope. Merial's (maker of Frontline and Heartguard) new non-adjuvanted UREVAX® Leukemia Vaccine that is administered with the VET JET(TM) transdermal system definitely addresses the two major risk factors of feline vaccinations. First, it is administered without the use of needles. It delivers a low-volume dose of vaccine through a tiny orifice into the cat's skin, subcutaneous tissue and muscle in less than a second. Through this method, the vaccine is deposited into the immune-cell-rich layers of skin and underlying tissue. Secondly the vaccine does not contain adjuvants. It is important for all cat owners to remember that feline leukemia is a highly contagious viral disease that can drastically impair the immune system. This deadly virus spreads easily through social grooming, shared food and water bowls, bite wounds and common litter boxes (or common potty locations outdoors).
Kittens also can contract feline leukemia from their mothers while still in the womb as well as through nursing and by grooming. Feline leukemia contributes to other infectious diseases by suppressing the immune system. It can also cause a deadly anemia by suppressing bone marrow production. For cats that contract feline leukemia, 50 percent die within six months and the others usually within three years. With these types of facts it is critical to discuss with your veterinarian your cat's risk factors and decide if the feline leukemia vaccine should be a part of your cat's vaccination protocol. Another critical point for all cat owners to realize is the importance of knowing your cat's feline leukemia and FIV (feline immunodeficiency virus) status. All cats/kittens should be tested through a simple clinic blood test. Once your cat's status is known, your veterinarian can recommend when and how often your cat will need to be retested.