Immunological aspects of mammary tumors in dogs and cats: a survey including own studies and pertinent literature

Naturally occurring cancer in companion animals parallels cancer in man more closely than does experimentally induced cancer in inbred laboratory animals. In dogs and cats, as in man, a role for immune responses is indicated in the development of tumors. A survey is presented based on the literature and our own studies concerning the immunological and immunotherapeutic aspects of canine and feline mammary neoplasia. In dogs bearing mammary neoplasms, circulating immune complexes appear to play a negative role in the generation of effective antitumor immune responses. The functional role of peripheral blood lymphocytes and tumor-infiltrating lymphocytes in dogs and cats with mammary tumors is not yet fully established. No tumor antigen responsible for humoral or cellular responses has yet been identified. Extracorporeal perfusion of serum of dogs with mammary tumors and subcutaneous administration of mitomycin- and neuraminidase-treated autologous tumor cells are associated with improved prognosis. The opposite was true for i.v. treatment with BCG or Corynebacterium parvum vaccine in our study, in contrast to a previous report. A number of other treatment modalities in cats and dogs with mammary carcinomas failed to induce tumor regression. Canine and feline mammary carcinomas are good candidates for modern immunotherapeutic approaches.