Snake urinary system — elongated kidneys and no bladder
Overview of the snake urinary tract — paired elongated kidneys staggered along the rear third of the body, nitrogen excreted as semi-solid uric acid, ureters opening into the cloaca, and no urinary bladder at all.
General educational reference only — not clinical or veterinary advice. Anatomy varies between individual animals; consult a licensed veterinarian for any health concern.
Staggered, elongated kidneys
Like the other paired organs in a snake's tubular body, the kidneys are long, narrow and staggered, the right lying cranial to the left in the rear third of the trunk. Each is divided into many lobules arranged one after another along its length, drained by a ureter running back toward the vent. The elongation and offset are the same packing solution seen in the snake's lungs and reproductive organs.
Uric acid and water economy
Snakes are uricotelic: nitrogenous waste is converted mainly to uric acid rather than to urea. Reptilian nephrons lack the loop of Henle, so the kidney cannot concentrate urine above the concentration of the blood; water is conserved instead by excreting nitrogen as poorly soluble uric acid, which is voided as a white to cream semi-solid urate paste carrying very little water. Further water and salts are reclaimed after the kidney, in the cloaca and adjoining colon, before waste leaves the body.
No bladder: ureters, cloaca, and the renal portal system
Snakes have no urinary bladder and no urethra. Each ureter opens directly into the urodeum, the middle chamber of the cloaca, which the reproductive tract also enters; a normal dropping therefore combines dark fecal material with white urates. As in other reptiles, a renal portal system can route venous blood from the tail and caudal body through the kidneys before it returns to the general circulation.
