A 14-year-old neutered female domestic shorthair was presented for evaluation of an interscapular mass. The lesion was 5.4 x 4.5 x 2.2cm in size, firm and multilobular. Samples taken with an incisional biopsy had identified it as a fibrosarcoma and a computed tomography scan showed that its position was closely adjacent to a microchip implant.
As the cat had previously been vaccinated at the same site it was not possible to establish the chip as the definitive cause of the fibrosarcoma but similar lesions have been associated with such implants in dogs and rodents.
The authors note that inflammation may predispose felines to tumour formation and highlight the need for separation and observation of vaccination and implantation sites. They also recommend adherence to guidelines on vaccination produced by the American Association of Feline Practitioners.
Journal of Feline Medicine and Surgery 10 (2): 202-205.
Abstract reproduced by kind permission of Veterinary Practice magazine