Canine Transmissible Venereal Sarcoma: Transplantation Studies in Neonatal and Adult Dogs2

Abstract

The transplantation of 2 spontaneous canine transmissible venereal sarcomas (CTVS) showed that the subcutaneous inoculation of 1 × 108 viable tumor cells consistently produced positive tumor takes in 16 days in 88% (15/17) of non-preconditioned adult mongrel dogs. After a period of rapid growth, the tumor regressed spontaneously in 2–6 months. Sixteen newborn puppies from normal mothers developed malignant neoplasms within 15 days after inoculation. These grew quickly, enlarged, ulcerated, and metastasized to other organs. In contrast, 36 of 43 puppies (84%), whose dams either failed to develop tumors or had borne tumors in our laboratory, developed tumors. Some of the 36 puppies with neoplasms had latent periods of up to 67 days, and the tumors invariably grew much more slowly than in puppies from unexposed dams. Spontaneous regression was seen in about 20% of the animals. The growth pattern of the tumor, benign or malignant, seemed to reflect the immunologic competence of the host, i.e., benign in normal adults and malignant in puppies. There appeared to be an inverse relationship between the maximum size the tumor attained and the proportion of small lymphocyte-like cells present in the viable tumor cell suspension. In contrast to previous reports, present findings on malignant behavior of experimental CTVS in normal puppies indicate the possible usefulness of this neoplasm for studies of experimental therapy.