Transmission of a chronic lymphoproliferative syndrome in ferrets

Lymphomas and leukemias are caused by transmissible viruses in a wide variety of species, including humans, cattle, and cats. Features of lymphoma in ferrets suggest that it, too, may have an infectious etiology. No agent has been identified.

Cells or cell-free inocula from a ferret with spontaneous malignant lymphoma were administered i.p. to six recipient ferrets. Two ferrets received fresh cells, two received frozen cells, and two received cell-free culture supernatant. The recipients were monitored routinely clinically and hematologically, and lymphoma was confirmed histologically. The lymphomas were characterized using cytology, cytochemistry, immunophenotyping, and histology. Cultivated cells from the donor and recipients were examined using reverse transcriptase assay, microscopy, and electron microscopy.

All of the six recipient ferrets developed mild sustained lymphocytosis within 6 weeks of the inoculation. Two of six were euthanized 14 to 18 months after inoculation. Lymphoma was later diagnosed in three of the four remaining ferrets at 24 to 36 months after inoculation. All developed a chronic indolent syndrome featuring profound splenomegaly, lymphocytosis with atypia, and histologically polymorphous lymphoma. Two of the three who developed lymphoma had received fresh donor lymphoma cells, and the third had received supernatant from donor cell cultures with elevated reverse transcriptase activity. Cultivated cells from the affected ferrets demonstrated reverse transcriptase activity and retrovirus-like particles.

This study demonstrates horizontal transmission of malignant lymphoma in ferrets using cell or cell-free inocula. Clinical and pathologic features of this syndrome in ferrets resembled virally induced lymphomas in other species.