Enucleation and the appearance of second primary tumors in cats bearing virally induced intraocular tumors.

The effect of enucleation of an eye containing a malignant intraocular neoplasm on the occurrence of secondary tumors was studied in cats with tumors, mainly melanomas, induced by Gardner feline fibrosarcoma virus. Enucleation of eyes containing progressively growing tumors was followed by a sharp increase in the frequency of secondary tumors. Secondary tumors were detected in 13 of 14 (92.8%) cats subjected to enucleation but in only seven of 21 (33.3%) untreated cats. The data suggest that the secondary tumors were not metastases but rather second primary tumors induced by local transformation of fibrosarcoma virus shed from the intraocular neoplasms. The increased incidence of these second primary tumors in cats subjected to enucleation was associated with depressed antibody titers to a tumor-specific transplantation antigen, the feline oncornavirus-associated cell membrane antigen.