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Feline Injection Site Sarcomas

Shaw, S. C., M. S. Kent, et al. (2009). “Temporal changes in characteristics of injection-site sarcomas in cats: 392 cases (1990-2006).” Journal of the American Veterinary Medical Association 234(3): 376-380.

The first suggestion that vaccine injections and the development of sarcomas in cats were associated was in October, 1991. Histologic and epidemiologic evaluations have supported a causal relationship between injections and the development of sarcomas. The most commonly indicated vaccines were those for rabies virus and feline leukemia (FeLV). In November 1996, the Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) was formed and one of its original tasks was to standardize injection sites. Prior to the recommendations, the majority of vaccinations were given in the interscapular region. The VAFSTF recommendations were to administer the rabies vaccine in the right rear leg as distal as possible, the FeLV vaccine in the left rear leg as distal as possible, and the FVRCP in the right shoulder. This study examined injection-site sarcomas (ISS) in 392 cats in order to evaluate changes in anatomic location and histologic classification of these sarcomas and the signalment of affected cats before and after publication of the VAFSTF recommendations. The results of the study indicated a high proportion of ISS in the interscapular region prior to publication of the recommendations (53.4%) and a significant proportional decrease (39.5%) after publication and likely adoption of the recommendations. There was also a significant decrease in lateral thoracic ISS that suggested tumors in these locations might have been caused by interscapular injections that were aberrantly administered. However, after 1996 the proportion of ISS on the limbs of cats and on the lateral aspects of the abdomen increased. This creates cause for concern because lateral abdominal tumors can be challenging, if not more difficult to treat, than those in the interscapular region. These results lead the authors to recommend that the VAFSTF recommendations be adhered to more strictly with emphasis on placement of injections in limbs as distally as possible. [VT]
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Related articles:
Romanelli, G., L. Marconato, et al. (2008). “Analysis of prognostic factors associated with injection-site sarcomas in cats: 57 cases (2001-2007).” J Am Vet Med Assoc 232(8): 1193-9.
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Kirpensteijn, J. (2006). “Feline injection site-associated sarcoma: Is it a reason to critically evaluate our vaccination policies?” Vet Microbiol 117(1): 59-65.
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