Usefulness of (99m)Tc(V)-dimercaptosuccinic acid scintigraphy in the assessment of response to external radiation therapy in soft tissue sarcoma in Giant Snauzer dog

A nine-year-old male black Giant Schnauzer dog was referred for the scintigraphic evaluation with a history of malignant fibrosarcoma with a rapidly growing non painful mass on the left shoulder region quite near to the site of an operation performed four months ago. We carried out oncological scintigraphy using pentavalent (99m)Technetium labelled dimercaptosuccinic acid [(99m)Tc(V)-DMSA], a tumour localising radiopharmaceutical agent. The study was performed to assess the margins, vascularity of the tumour and response to the cancer therapy. Uniform intense radiopharmaceutical uptake was observed in the lesion indicating its margins, vascularity and malignant nature. The dog was subjected to external radiation therapy to control the growth of the cancer and to bring the tumour mass to an operable size. The dog was followed up with (99m)Tc(V)-DMSA scintigraphy pre-irradiation and post-irradiation. Immediately after the post-irradiation scintigraphy, the dog was operated on. During the surgery, resection of the tumour margins was performed carefully using a hand held gamma probe to assure that no tumour tissue was left inside. In conclusion, the authors would like to state that (99m)Tc(V)-DMSA oncoscintigraphy is valuable in the assessment and evaluation of therapy in canine soft tissue cancer.