COMPARISON OF FIBROSARCOMAS THAT DEVELOPED AT VACCINATION SITES AND AT NONVACCINATION SITES IN CATS - 239 CASES (1991-1992)

Questionnaires were sent to veterinarians who had submitted a fibrosar coma from a cat to the surgical pathology services of the veterinary s chools of the University of Pennsylvania and Tufts University between Jan 1, 1991 and June 30, 1992. Questionnaire items included signalment , FeLV and feline immunodeficiency virus status, site of sarcoma, vacc ination site, vaccines used, treatment, biologic behavior of the tumor , and final outcome. Data were analyzed, using Student's t-test for co ntinuous data, X2 test fo categoric data, and log-rank test for surviv al estimates. Comparing results for cats with vaccination-site (vs) tu mors and nonvaccination-site (nvs) tumors, we determined that vs tumor s developed in younger cats and were larger thant nvs tumors. Although vs sarcomas were biologically aggressive and redeveloped more often t han nvs sarcomas,metastasis was not detected, and cats with ns tumors survived longer than cats with nvs tumors. Vaccination-site sarcomas d eveloped in cats after injection of many types of vaccines, administer ed singularly or in combination. Of the cats in the vs group administe red a single vaccine, 37% were given rabies, 33% were given feline vir al rhinotracheitis/calcivirus/panleukopenia virus, and 30% were given FeLV vaccines. Cats with vs tumors were more likely to have received F eLV vaccine and less likely to have received rabies vaccine than those with nvs sarcomas, it was believed that this probably represented mar keting practices and brand popularity. Many of the vaccines used had a luminum and other highly immunogenic adjuvants. We hypothesized that r esident fibroblasts and myofibroblasts proliferated in the cats in res ponse to injected adjuvants or other vaccine components, and, in some cats, these cells eventually underwent neoplastic transformation.