Canis ISSN: 2398-2942

Anesthetic monitoring: urine output

Contributor(s): Sheilah Robertson



  • In the absence of primary renal disease and obstruction of outflow the volume of urine produced depends on the renal blood flow.
  • Thus urine output can be used as an indicator of tissue perfusion.
  • Adequate urine flow can be used as an indicator of adequate tissue perfusion throughout the body.
  • Normal values are 1-2 ml urine/kg/hour.


  • If urine output falls below 1 ml/kg/hour, corrective measures to improve tissue perfusion can be implemented.
  • In the absence of response to an appropriate intravenous fluid infusion Fluid therapy , further investigation of oliguria or anuria is indicated.
  • As a specific monitoring aid in the anesthesia of animals with pre-existing renal disease Anesthesia: in renal insufficiency.


  • Simple technique.
  • Equipment required is inexpensive.
  • Allows remote monitoring of tissue perfusion when close access to the animal is difficult and without disturbing surgical drapes.


  • Repeated catheterization should be avoided as this increases the risk of introducing infection into the bladder and of traumatizing the urethra.


  • Collect all necessary equipment.
  • Be prepared to perform the procedure prior to final positioning and draping of the animal.


  • Self-retaining catheter or standard urinary catheter plus materials for suturing or fixing it in situ.
  • Giving set or drip extension tubing, and any necessary adaptors.
  • Calibrated bottle or empty fluid infusion bag. Alternatively, a three-way tap, spigot or clamp can be used to prevent outflow of urine until it is withdrawn manually and measured.
  • Sterile lubricating jelly.
    All equipment must be sterile


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Refereed papers