This case report describes a Thoroughbred broodmare presented for colic and pyrexia. The mare had a history of repeated urinary tract infections, placentitis, abortion and endotoxaemia. A diagnosis of bilateral subcapsular renal haematoma was made by ultrasonography and standing laparoscopy and confirmed on post-mortem. Trauma, clotting disorder, and neoplasia were ruled out as a cause of the bleeding. However, histopathology revealed severe, diffuse, acute fibrinosuppurative tubulointerstitial nephritis with degeneration of vascular walls, suggesting that this has caused renal bleeding and development of subcapsular hematomas.