Urothelial cell carcinoma of the bladder causing severe hemorrhage and hypovolemic shock in a cat.

Case summary: A 7-year-old female spayed domestic shorthair cat was evaluated for a 10-day history of progressive hematuria. Abdominal ultrasound revealed a large non-shadowing echogenic mass in the bladder lumen and multiple small broad-based pedunculated lesions along the luminal urinary bladder wall. The cat was progressively anemic, tachypneic and lethargic, and required a whole blood transfusion. The following morning, peracute bradycardia, bradypnea and unresponsive mentation were noted. A unit of packed red blood cells (pRBCs) was rapidly administered to the patient, resulting in improved cardiorespiratory and mental status. Cystoscopy revealed a blood clot occupying approximately 50% of the bladder lumen, multiple proliferative broad-based masses originating from the bladder wall and two pulsatile bleeding vessels associated with one of the masses. Biopsies of the masses were obtained, followed by electrocautery of the bleeding vessels and sclerotherapy of the entire urinary bladder. Another transfusion with pRBCs was administered the following day, and the patient was discharged 48 h after cystoscopy. The biopsies were consistent with urothelial cell carcinoma, and meloxicam was prescribed. No additional blood transfusions were required, and the cat had resolution of anemia 20 weeks after discharge. Relevance and novel information: Urothelial cell carcinoma is the most common type of cancer of the bladder wall in cats. However, severe hemorrhage caused by this tumor resulting in hypovolemic shock has been poorly reported in cats. Treatment with electrocautery and sclerotherapy can lead to long-term control of bleeding when definitive treatment is not pursued.