Urothelial carcinoma is a malignant neoplasm of the urinary tract arising from the transitional epithelium. Its clinical manifestations often overlap with non-neoplastic conditions, such as urinary tract infections, thereby presenting a diagnostic challenge for clinicians. Differentiating from others condition is important, as the treatment and prognoses vary significantly. This case report presented a ۴-year-old female local dog, weighing ۱۱.۵۵ kg in BVC Animal Hospital with a primary complaint of hematuria. Clinical, hematological, and serum biochemical evaluations revealed no significant abnormalities. Ultrasonographic (USG) examination identified a hypoechoic mass measuring ۰.۳۱×۰.۸۵ cm located within the lumen and thickening of urinary bladder wall. Cytological assessment was performed via urine catheterization. The cytological specimen demonstrated a population of cells with anisocytosis, anisokaryosis, and a high nucleus-to-cytoplasm ratio, raising suspicion of a malignant tumor. Consequently, biopsy was performed via cystotomy to establish a definitive diagnosis. Prior to release the histopathological results, post-cystotomy the dog was treated with cefadroxil as antibiotics at ۲۰ mg/kg BW b.i.d for ۱۴ days, carprofen as anti-inflammatory at ۲ mg/kg BW s.i.d. for ۵ days, and tramadol as analgesics at ۲ mg/kg BW b.i.d. for ۵ days. Histopathological examination showed a non-encapsulated tumor with well-defined demarcation in the mucosa. The tumor consists of a dense population of epithelial tumor cells without evidence of invasion, confirmed the diagnosis of non-invasive, non-papillary urothelial carcinoma (in situ). The patient was managed palliatively with the administration of piroxicam at ۰.۳ mg/kg BW s.i.d as monotherapy. Until day ۱۹۰, the dog showing a stable disease. To the best of the authors’ knowledge, this is the first documented case of canine urothelial carcinoma in Indonesia
