Effects of Prolonged Anesthesia with Enflurane or Halothane on Renal Function in Dogs

Elevated serum inorganic fluoride levels (60–300 μmol/l), maintained over 6 h, influenced renal function in beagle dogs. Changes in water reabsorption were seen with an increased urine flow and free water clearance and decreased urinary concentration capacity. Possible nephrotoxicity as an effect of inorganic fluoride production during prolonged enflurane anesthesia was evaluated in a group of beagle dogs. Another group of dogs, anesthetized with halothane in equianesthetic doses, was studied for comparison. Serum inorganic fluoride levels and urinary oxalate excretion were determined and postanesthetic renal morphology was examined. Renal function was evaluated from endogenous clearances and concentration capacity before and after anesthesia. In the enflurane group, serum inorganic fluoride levels peaked at 22.5 μmol/1 at the end of anesthesia and decreased rapidly in the postanesthetic period. Urinary oxalate excretion did not increase. No changes in renal morphology were found. Renal function tests did not reveal any disturbance after enflurane anesthesia. The two anesthetized groups did not differ in any of the parameters studied, except in serum inorganic fluoride levels.