Case Description- A seven-year-old female terrier dog with a large mass in the posterior aspect of the right thigh was referred to the Veterinary Clinic of Shahid Bahonar University of Kerman. Clinical Findings- The hyperpigmented mass without any sign of inflammation, pain and redness was seen at the right thigh. Treatment and Outcome- The abnormal mass was removed surgically. Histopathlogic examinations confirmed the occurrence of myxoma. Clinical Relevance - Myxoma is a rare tumor in domestic animals especially dog and surgical treatment is the choice.