A landmark study, World Wide Web-based survey of vaccination practices, postvaccinal reactions, and vaccine site-associated sarcomas in cats was published in the May 15, 2002 issue of The Journal of the American Veterinary Medical Association (JAVMA). The article was written by Glenna Gobar, DVM and Philip Kass, DVM, Ph.D. The purpose of the study was to better quantify the incidence of vaccine site-associated sarcomas and calculate the incidence of postvaccinal reactions by determining the frequency of malignant transformations.

The study concluded that the incidence of vaccine site-associated sarcomas is low and not increasing.

93 veterinarians completed the study
31,671 cats were studied
61,747 doses were administered to these cats

2 sarcomas were noted that meet the criteria established by the study design:

• One sarcoma was found in a cat that received an adjuvanted rabies vaccine.
• One sarcoma was found on a 13.5-year-old patient that received a combination FeLV and FVRCP+C vaccine without adjuvant.

Some other points discussed in the paper worth noting:

• Results of the study do not support the contention that vaccine site-associated sarcomas are as common as has been suggested.
• The findings from this study concerning postvaccinal reactions should be reassuring to practitioners. Approximately 98 percent of the postvaccinal reactions resolved without medical intervention. Ninety-six percent resolved within three months and 100 percent within four months of vaccination. Such information could possibly convince those who might otherwise decline vaccinations for their pets to reconsider.

Jack Stephens, CEO/Founder of Veterinary Pet Insurance, the nation's largest provider of pet health insurance, agrees. "We had just 12 sarcoma claims in 2001 and 14 in 2002, or about 0.01 percent of the claims. It's an extremely small problem, and one we worry about much less than what would happen if people stopped vaccinating.''

Further independent research should help to better define the potential causes (and solutions) for the sarcoma issue; including the role of genetics in predisposing some cats to sarcoma occurrence.

###