In case of very violent congestion, extensive sanguineous extravasation may occur, leading even to rupture of the capsule and the escape of blood into the perirenal adipose tissue or into the abdominal cavity. Cases of this kind in the soliped are recorded by Caroni, Cadeac, Moussu, Kitt, Zundel, Mollereau and Porcher. Averons describes in the _Revue Veterinaire_ (1897) a case in which both kidneys were surrounded by an immense black clot, and weighed no less than 36 lbs. Leblanc records a similar case affecting the one kidney. The mass measured about 10 inches by 8. _Symptoms._ These are liable to appear suddenly, often while the patient is at work, and are manifested by weakness in the loins, slow gait or sudden stopping, the hind limbs are held in abduction, and advanced with apparent stiffness and pain. There is much excitement and anxiety, the face is pinched and strained, the respiration accelerated, the pulse hard, tense and rapid, and the eyes or nose may be turned toward the flank or loins. There may be colicy pains, with uneasy movements of the tail and hind limbs, pawing, and even lying down and rolling. The visible mucosæ are strongly injected and in bad cases the skin may be drenched with sweat. There is at first little or no hyperthermia. At first there may be no micturition but in an hour or more, urine may be discharged in excess, sometimes as much as 25 quarts, and of a low specific gravity (1001 to 1005). If there has been no blood extravasation it is usually clear and limpid but with extravasation it may be of all shades of pink or red to black. In the latter case the suffering is liable to be acute (Cadeac), and contrary to the condition in hæmoglobinuria, the urine contains blood globules and even tubular coagula representing the uriniferous tubes and entangling the blood cells. This is complicated by albuminuria. _Course. Duration._ The congestion is short lived. It speedily undergoes resolution with the passage of normal, clear urine, and the recovery of appetite and spirit, or it becomes rapidly aggravated, with continuous suffering and colic, complete loss of appetite, dullness, constant decubitus, weakness, debility, small or imperceptible pulse, palpitations, darker color and perhaps complete suppression of urine, and stupor or other nervous disorder. Death may occur on the fourth to the sixth day. It may be delayed by a partial recovery followed by a relapse. _Diagnosis._ Acute renal congestion is distinguished from _nephritis_ by the suddenness of the onset, the absence of fever and the comparative absence of tenderness of the loins, and of tubular casts.