Brain Metastasis In A Case Of Canine Transmissible Venereal Tumor After A Supposed Successful Treatment With Vincristine Sulfate

A ten year old mongrel bitch was diagnosed with a primary vulvar transmissible venereal tumor (TVT) causing subcutaneous, mammary and splenic metastasis and it was successfully treated with vincristine. Four months later the animal presented neurological disturbances, brain metastases were suspected and the animal was euthanized. A TVT metastatic mass was found in the brain and confirmed with immunohistochemical results, being positive for vimentin and lysozyme and negative for S-100, CD3 and cytokeratin. TVT metastases in the brain are a rare event and cannot be treated with usual chemotherapy as vincristine does not cross the blood-brain barrier, thus allowing the re-emergence of the tumor after a period of time.