2023 Volume 76 Issue 8 Pages e202-e207
An 8-year-4-month-old male Bernese Mountain dog was referred to the Obihiro University of Agriculture and Veterinary Medicine because of a pulmonary mass. The dog was diagnosed with pulmonary histiocytic sarcoma, and a lung lobectomy was performed. The pulmonary mass was confirmed to be histiocytic sarcoma by histopathological examination. We discovered a subcutaneous mass 5 cm in diameter on the right side of the hind flank on the fifth administration of lomustine (on day 119). It was diagnosed as metastatic lesion of histiocytic sarcoma by cytological examination. Therefore, we started administering doxorubicin instead of lomustine, but no effect was observed, and the metastatic lesion increased to a diameter of 11 cm. Then, we started treatment with toceranib phosphate on day 172. The metastatic lesions rapidly regressed. However, on day 301, the re-enlargement of the metastatic lesion in the hind flank and pleural effusion were observed. The patient was treated with vincristine, but died on day 318 without any response. The present case appears to be a rare case in which toceranib phosphate had a dramatic effect on canine histiocytic sarcoma.
