A 3-year-old, male Shih-tzu dog with clinical signs of dysuria and hematuria was brought to the Veterinary Teaching Hospital. Chonnam National University. The patient was suspected urolithiasis by history taking and clinical signs but urinary and urethra calculus was not found in the radiographic examination. Enlarged prostatic gland (29.0$ imes$28.0 mm) and severe finding of cystitis was observed from the ultrasonographic examination. The dog was finally diagnosed as the secondary urethral obstruction by benign prostatic hyperplasia. Castration was performed to treatment of acute hyperplasia of prostatic gland and prostatic cysts. After 26 days of operation, the prostate was defined small, hypoechoic, symmetric and decreased size (18.5$ imes$18.0mm) by ultrasonography and dysuria cured completely.