Urinary calculi associated with portosystemic shunts in six dogs.

Portosystemic shunts were diagnosed in 6 dogs with urinary calculi and signs of neurologic disease. Five of the dogs were initially examined because of neurologic signs, and 1 was seen because of urinary tract problems. The composition of the calculi was variable, but in all 13 episodes of calculi formation, the calculi contained an ammonium or uric acid component. One dog is being controlled under medical management; 4 of the dogs died, and 1 was euthanatized. The interpretation of pathogenesis was that decreased delivery of blood to the liver due to shunting or decreased liver function can potentially result in high blood concentrations of ammonia and uric acid, both of which are metabolic end products cleared by the kidneys; thus, the urinary tract would be an excellent environment for the precipitation of their salts.