A 14-year-old intact female, mixed dog was presented with hematuria and strangury. Mass in the abdominal cavity was seen on radiographs and ultrasound. On the cytological examination in the urethra, clusters of pleomorphic epithelial cell were found. Tissues of the urethra and the urinary bladder were obtained at the time laparotomy and determined the extent of the mass. Transitional cell carcinoma (TCC) of the urinary bladder was found in histopathologic characteristics. Urinary diversion after removal of a complete full section of the TCC in bladder wall was performed. Piroxicam, as a medical therapy for TCC, was orally administrated. Surgical operation and chemotherapy were selected with the goal of maintaining and improving quality of life.

Primary adenocarcinoma is a rare neoplasm of the urinary bladder, constituting approximately 2.5% of all primary bladder malignancies. Signet ring cell variant is even rarer, constituting approximately 0.5% to 2.0% of all primary carcinoma of the urinary bladder. However, glandular differentiation in the urinary bladder is relatively more common than primary adenocarcinoma of the urinary bladder. Therefore, diagnosis of primary adenocarcinoma of the urinary bladder can be very challenging, but of significant clinical importance. We report on a case of adenocarcinoma with mucinous and signet ring cell differentiation in the bladder dome in a 49-year-old female.