A 11 year-old, female, shih-tzu mixed-breed dog was presents with history of sudden blindness for 2 days. An ophthalmic test was conducted to find the cause of blindness, including an intraocular pressure test, a fundus test, and an electroretinogram. As a result of the test, the abnormality in the eye could not be confirmed, so MRI request was made. MRI confirmed mass areas with 1.0 × 0.5 mm T2W/FLAIR heterogeneous hyperintense, T1W isointense, and enhancement that spread widely from the dorsal part of the sella turcica to the anterior optical chiasm. Cystic lesion was identified in the front of the lesion, and it had the characteristics of an extra-axial tumor such as a broad base attachment surface and a dural tail signal. Based on these tests diagnosed blindness caused by brain tumors. Clinical symptoms began to improve three days after taking chemotherapy, and all clinical symptoms disappeared after a week. This case report demonstrated that clinical sign, diagnostic imaging and successful treatment result with chemotherapy in canine brain tumor patient.