Abstract
A twelve-year-old shih tzu dog was referred to us with progressive enlargement of the abdomen. Physical and radiographic examinations revealed a large abdominal mass surrounded by peritoneal fluid. The ascitic fluid was denatured and had high viscosity. On the 21st day, the dog had a surgical operation for resection of the mass to improve the dog's quality of life. The removed mass was weak and jelly-like, involving the right adrenal gland, and was diagnosed histopathologically as myxosarcoma. On the 73rd day, a second surgery was done because a similar fluid and mass were detected in the abdomen, which had become larger again. On the 115th day, recurrence was found again, but no further treatment was given at the pet owner's request. Although the dog died on the 133rd day, its quality of life had been better than it might have been without the repeated surgeries.
