Thyroid carcino-sarcoma in a dog.

An adult male greyhound was diagnosed with a thyroid carcino-sarcoma by means of histopathology and positive immuno-histochemistry staining for cytokeratin and vimentin. Surgery and radiotherapy of the area were successful in local tumour control. Adjuvant chemotherapy was recommended to treat and prevent further metastasis. The use of carboplatin, metronomic cyclophosphamide chemotherapy and toceranib failed to control the progression of distant metastasis. The survival time was seven months from the time of diagnosis. This is the eighth case of carcino-sarcoma of the thyroid documented in veterinary medicine and the first one treated with a multimodal approach based on surgery, radiotherapy and chemotherapy. As documented in human medicine, chemotherapy appeared to be ineffective to prevent or delay the progression of the metastatic disease in this case.