Understanding Subcutaneous Ureteral Bypass (SUB) in Cats: What Pet Owners Should Know (author is Sophia Avgeris, DVM DACVIM)


Urinary obstructions in cats, particularly involving the ureters, can be a life-threatening emergency. Ureteral obstructions are often caused by stones, strictures, or scarring that prevents urine from draining properly from the kidney to the bladder. When left untreated, this can lead to severe kidney damage or even kidney failure. 


Clinical signs of ureter obstruction include decreased appetite, increased water intake, discomfort, lethargy. Blood work might show changes related to renal disease as azotemia (increased BUN and increased CREA). In more severe cases cats might develop diluted urine. 


At Dogwood Veterinary Specialty and Emergency, our internal medicine doctors and surgeons are equipped to diagnose and treat these conditions and might recommend a Subcutaneous Ureteral Bypass (SUB) placement.


What is a SUB Device?
A Subcutaneous Ureteral Bypass (SUB) is a specialized medical device that reroutes urine flow from the kidney to the bladder by bypassing the obstructed ureter. 


When is a SUB Recommended?
SUB placement is typically recommended in the following situations:

  • Ureteral obstruction due to stones or strictures.
  • When ureteral stenting is not possible or has failed.
  • Bilateral obstructions (involving both ureters).
  • Recurrent obstruction after previous surgical interventions.

This procedure is often life-saving, especially for cats that do not respond to medical management or where other surgical options are not feasible.


What to Expect: Before, During, and After Surgery


Before Surgery
Your cat will undergo thorough diagnostic testing including bloodwork, urinalysis, abdominal imaging (ultrasound and/or CT), and stabilization of kidney function if needed.
Intravenous fluids and supportive care may be started to prepare your cat for anesthesia.


During Surgery

  • The procedure is performed under general anesthesia by a surgeon.
  • A small port will be placed under the skin, typically on the abdominal wall, for long-term access and maintenance.


After Surgery

  • Most cats are hospitalized for a few days postoperatively for pain management, IV fluids, and monitoring.
  • Kidney values will be rechecked to evaluate improvement in function.
  • The SUB device requires routine maintenance (typically flushing every 3) to prevent blockage and infection.


Long-Term Outlook

  • Cats with a SUB device can go on to live happy, comfortable lives. Long-term management includes:
  • Regular rechecks and imaging to ensure the device remains patent.
  • Periodic flushing of the device, which can be done under light sedation.
  • Monitoring for signs of urinary tract infection or other complications.


Why Choose Dogwood?
At Dogwood Veterinary Specialty and Emergency, we understand how stressful it is when your cat is sick. Our critical care, internal medicine and surgery teams have extensive experience managing complex urinary cases, and we are proud to offer SUB placement as part of our specialty services.


Our hospital provides:

  • 24/7 critical care for urgent cases.
  • State-of-the-art diagnostic imaging.
  • A dedicated surgical suite with experienced anesthesiologists and technicians.

If your primary veterinarian has diagnosed a ureteral obstruction or you would like to discuss the possibility of a SUB for your cat, we’re here to help.
For more information or to consult with our team, please reach out to us at info@dogwood.vet.