An 18-month-old, intact female German shepherd dog was presented for evaluation of severe, frank hemorrhage from the vulva. A complete blood count, serum biochemical analysis, and urinalysis supported acute hemorrhage. Abdominal radiographs were unremarkable. Abdominal ultrasound demonstrated that the uterine body and cranial vaginal lumen were fluid-filled and contained hyperechoic, polypoid masses that were suspected to be blood clots. Exploratory laparotomy revealed a mildly enlarged uterus with a diffuse, cystic endometrium; significant amounts of blood and blood clots within the lumen; and several focal accumulations of yellow fluid presumed to be a purulent exudate. Histopathology confirmed severe, cystic, endometrial hyperplasia and pyometra complex.