A case of fibrosarcoma located at medium portion of the urethra of a female dog which presented pollakiuria, estranguria and hematuria at the beginning of urination was reported. The patient also presented polyuria, polydipsia, emesis and anorexia for two days. The complementary exams lead to the diagnosis of bilateral hydronephrosis, right renal hypoplasy and a mass in the urethra causing a dorsal dilatation at its medium portion. A biopsy was not performed antemortem because the general condition of the patient, which even with the institution of treatment for chronic kidney disease, showed no progress. The retrograde cystourethrography and histopathology examinations were decisive to detect urethral fibrosarcoma. Ultrasonography and cytology through traumatic probe were inconclusive, due to the mass location and its exfoliating properties.
bitch; fibrosarcoma; urethra and cystourethrography