Canine
transmissible venereal tumors were studied for response to intralesional Bacillus Calmette-Guérin (BCG)
therapy. Six pairs of littermates, identical for the major histocompatibility complex, were evaluated. One member of each pair received intralesional BCG to one of two growing
tumors. Lesions of control animals received
0.9% NaCl solution. Both injected and noninjected lesions of BCG-treated animals underwent regression within 63 days, as compared to an extended period of
tumor growth (beyond 100 days) for controls (p less than 0.05). Serial in vitro assays during
therapy included; (a) mixed lymphocyte-
tumor culture, (b)
phytohemagglutinin stimulation, and (c) assessment of lymphocyte surface markers. Lymphocytes from BCG-treated dogs were significantly more responsive to
tumor cells in mixed lymphocyte-
tumor culture assay than were those from controls (p less than 0.05). Maximal responses occurred during
tumor regression. T- and B-lymphocyte levels as assayed by rosette formation and surface marker
immunoglobulins were not influenced by BCG
therapy. It was concluded that intralesional BCG
therapy of canine venereal
tumors was highly effective in causing regression of injected and noninjected lesions. This
tumor model system may be useful for the evaluation of the effectiveness of new immunotherapeutic approaches on established
neoplasms in large, randomly bred animals.