Efficacy of Lomustine in a Dog with Histiocytic Sarcoma on the Cardiac Base

Abstract

An intrathoracic mass was found in a 10-year-old spayed Golden Retriever at the base of the heart by chest radiography. Approximately one month later, the dog was referred to our hospital because of coughing and vomiting. Exploratory thoracotomy and an incisional biopsy of the mass were performed on the 39th day after the initial examination. A histopathologic diagnosis of histiocytic sarcoma (HS) was made. Treatment with lomustine (CCNU) at a dose of 40 mg/m² po was performed every three weeks. The clinical signs improved, and the intrathoracic tumor diminished significantly in size. Over the course of 17 administrations of lomustine, severe side effects were not observed, and recurrence and metastasis were not observed until the dog died on the 569th day. Therefore, lomustine is suggested as useful in the treatment of canine histiocytic sarcoma.