Temporal changes in characteristics of injection-site sarcomas in cats: 392 cases (1990-2006)

Objective-To evaluate changes in characteristics of feline injection-site sarcomas (ISSs) from 1990 through 2006. Design-Retrospective case series. Animals-392 cats with a histologic diagnosis of soft tissue sarcoma, osteosarcoma, or chondrosarcoma at potential injection sites. Procedures-Classification and anatomic location of tumors and signalment of affected cats were compared between ISSs diagnosed before and after publication of the Vaccine Associated Feline Sarcoma Task Force vaccination recommendations in 1996. Results-From before to after publication of the vaccination recommendations, proportions of ISSs significantly decreased in the interscapular (53.4% to 39.5%) and right and left thoracic (10.2% to 3.6% and 9.1% to 1.3%, respectively) regions. On the other hand, proportions of ISSs significantly increased in the right thoracic limb (1.1 % to 9.5%) and the combined regions of the right pelvic limb with right lateral aspect of the abdomen (12.5% to 25.0%) and the left pelvic limb with left lateral aspect of the abdomen (11.4% to 13.8%). Patterns of tumor classification and signalment did not change. Conclusions and Clinical Relevance-Despite publication of the vaccination recommendations, a high proportion of tumors still developed in the interscapular region. There was also an increase in lateral abdominal ISSs, which are more difficult to treat and are likely attributable to aberrant placement of injections intended for the pelvic limbs. Veterinarians are complying with vaccination recommendations to some extent, but they need to focus on administering vaccines as distally as possible on a limb to allow for complete surgical margins if amputation of a limb is required.