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Artificial Urethral Sphincter (AUS)

Urinary incontinence <skip to artificial urethral sphincter discussion>

  • Involuntary leakage of urine out of the urethra (the tube draining the bladder and emptying out the penis or into the vagina). 
  • It should be distinguished from:
    • Submissive behavior (in which a pet may squat or roll onto its back and void urine)
    • Accidents associated with excessive urine production (such as from decreased kidney function, Diabetes mellitus, etc.)
    • Accidents resulting from having to void frequently due to urinary tract infection or inflammation.
  • If your veterinarian has determined that your pet has true urinary incontinence, an evaluation should be done to rule out:
    • Ectopic ureter – the tube delivering urine to from the kidney deposits the urine in the urethra (the tube from the bladder out of the body) or possibly the vagina, rather than the bladder, where it is normally stored.
    • Ectopic ureter is a surgical disease requiring a different treatment.
    • Other congenital (present at birth; or “birth defect”) anomalies of the urinary or reproductive tract.
    • Neurologic issues involving the spine or peripheral nerves
    • Numerous other causes affecting continence. 
  • Primary urethral sphincter mechanism incompetence (USMI) is the failure of the urethra to maintain sufficient pressure to prevent urine from leaking out of the bladder when the pet is not actively urinating. 
    • Most common in female dogs, and often occurs with age and/or following  ovariohysterectomy (spaying)
    • Can occur in male dogs, and dogs of any age. 
    • As always, your veterinarian should make this diagnosis following a thorough evaluation.
    • A number of medical therapies exist for USMI, including hormone therapy and phenylpropanalamine (Proin), each with various potential side effects.
      • significant number of pets maintain moderate to severe levels of incontinence despite medical therapy.

I recommend the Artificial Urethral Sphincter (AUS), also referred to as the hydraulic occluder.

Procedure
  • Limited surgical approach to the urethral just caudal (behind; in the direction of the tail) to the urinary bladder
  • Placement of a cuff around the urethra
  • Cuff is connected to a subcutaneous (under the skin) inguinal (groin) port
  • Cuff can be inflated or deflated to provide continence without obstruction. 

Results (case series of patients receiving the AUS)

  • Every patient (18/18) showed an improvement of continence
  • 70% were fully continent
  • 92% had functional continence, meaning rare accidents occurred, but the pets were continent on a consistent basis. 
  • Compares favorably to other surgical procedures intending to improve urinary continence.

If you wish to discuss whether your pet is a candidate for the Artificial Urethral Sphincter, please have your veterinarian contact our board-certified surgeon, Dr. Jeff Christiansen, either by e-mailing Dr. Christiansen or by calling him (your veterinarian should have his phone number, or can get it via e-mail).
     If indicated, you may schedule an appointment with Dr. Jeff Christiansen at the clinic of your choice, to evaluate your pet and to discuss the Artificial Urethral Sphincter to improve your pet's length and quality of life.
     
If you have additional questions, please feel free to directly e-mail Dr. Christiansen

For more information on urinary incontinence, see the article on urinary incontinence on Washington State University’s ​page.

The Artificial Urethral Sphincter was developed by – and the images are courtesy of – Norfolk Medical