Vaccine-Associated Feline sarcomas: A summary of USP DATA.

E. Kathryn Meyer, VMD  United States Pharmacopeia, Rockville, MD

USP: The United States Pharmacopeia (USP) is a private, not for profit organization established in 1820.  Although most of USP's efforts involve "human" medicine, a reporting program dedicated to veterinary medicine was launched in 1994.  The Veterinary Practitioners' Reporting (VPR) Program is presented in cooperation with the AVMA and is operated by USP as a free service for veterinary practitioners.

Database: Since its implementation, the VPR program has received 1,598 reports associated with products used in veterinary medicine.  Copies of reports are forwarded to the manufacturer, the appropriate regulatory agency, and the AVMA.  Report information is entered into USP's database, where it is easily retrieved for analysis.  This is a voluntary reporting program and data must be interpreted with this in mind.

Feline Sarcomas: In addition to serving as a central repository for reports of vaccine-associated sarcomas, USP has supported the efforts of the Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) by mailing copies of VAFSTF vaccination recommendations directly to the AVMA members and by collaborating with Dr. Phillip Kass (UC Davis), coordinator of a VAFSTF-funded epidemiological study to determine risk factors for vaccine-associated sarcoma development.  As of 8-7-98, 169 reports of suspected vaccine-associated feline sarcomas resided in the USP database.  Data extracted from these sarcoma reports provide descriptive information which may be useful for consideration in future vaccination guidelines and treatment recommendations.

Signalment: Of the 169 cats in these reports, the large majority (159) were domestic breeds.  Both males (43%) and females (57%) were represented.  At the time of tumor diagnosis, the age of the cats ranged from 2 to 19 years.

Types of vaccines involved: Although concern regarding vaccine-associated sarcomas has historically focused on Rabies and FeLV vaccines, reports of tumors arising post- FVRCP+/Chlamydia administration have been submitted to USP.  Of the 243 vaccines that may have been associated with sarcoma development in 169 cats, 100 were Rabies (41%), 79 were FVRCP+/-C (33%), 49 were FeLV (20%), and 15 were FVRCP+/-C/FeLV combination vaccines. In 17 reports, the FVRCP+/-C vaccine was documented as the last vaccine to be administered in the area prior to sarcoma development.  In 3 of these cases, the reporter specifically indicated that the FVRCP+/-C was the only vaccine that had ever been administered  at the site.  Both modified live and killed FVRCP+/-C vaccines are represented.

Time from vaccine administration to tumor detection: Although times ranged  from less than one month to 13 years; 133 cats (93%) developed tumors less than 4 years following vaccination.  Indeed, 85 cats (59%) were diagnosed within 1 year of vaccination and, despite some clinical observations that sarcomas rarely develop within 3 months of vaccination, one fourth (36/143) of the cats in the USP reports developed sarcomas within 3 months (<1 month (11 cats), 1 to 2 months (14 cats), 2 to 3 months (11 cats).  This  information may warrant consideration with regard to how long a vaccine "lump" is watched prior to biopsy.

More reporting: Reporting suspected vaccine-associated sarcomas to (800-487-7776) or The Veterinary Practitioners' Reporting (VPR) Program is encouraged to increase the understanding of this disease.

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