Subcutaneous Ureteral Bypass Surgery for Cats
A S.U.B. device creates a bypass between the kidney and the bladder when a cat's ureter is obstructed, restoring urine flow and protecting renal function.
Ureteral obstruction in cats
Ureteral obstruction is a surgical emergency in cats. The ureter is extremely narrow, and a single stone (ureterolithiasis), a stricture or a blood clot can block urine flow from the kidney to the bladder. Pressure builds up in the renal pelvis (hydronephrosis) and kidney function deteriorates quickly.
Many cats have chronic kidney disease in the other kidney at the same time, which makes rapid decompression of the obstructed side critical.
- Lethargy, reduced appetite and vomiting
- Rising creatinine and SDMA on bloodwork
- Ureteral stones or hydronephrosis seen on ultrasound or radiographs
- Deterioration despite medical management
Diagnosis before surgery
- Abdominal ultrasound to confirm hydronephrosis and locate the obstruction
- Radiographs to identify radiopaque ureteroliths
- Full bloodwork, electrolytes and blood pressure
- Urinalysis and urine culture
- Assessment of overall renal function and anaesthetic risk
The S.U.B. procedure
The device consists of a nephrostomy catheter placed in the renal pelvis and a cystostomy catheter in the bladder, connected to a subcutaneous port. Urine bypasses the obstructed ureter completely.
Placement is performed under general anaesthesia with imaging guidance. The subcutaneous port allows the system to be sampled and flushed afterwards without further surgery.
Hospitalisation and aftercare
Cats are hospitalised after surgery with intravenous fluids, analgesia and continuous monitoring of urine output, electrolytes and renal values. Staff are present 24 hours a day.
Long-term management includes periodic flushing and maintenance of the S.U.B. device, urine cultures to detect infection, and dietary management to reduce stone recurrence. We provide a written follow-up protocol that your own veterinarian can carry out.
International cases
S.U.B. surgery is not available in every region, and in some countries it is quoted at a very high cost. Send us your cat's ultrasound report, radiographs and bloodwork and our surgical team will review whether a subcutaneous ureteral bypass is indicated.
Because ureteral obstruction is time-sensitive, cases that are already unstable are usually better stabilised locally first. We will tell you honestly whether travel is realistic for your cat.
Frequently asked questions
Is it a subcutaneous ureteral bypass or a urethral bypass?
Ureteral. The device bypasses the ureter — the tube between the kidney and the bladder — not the urethra.
How long does my cat stay in hospital?
Most cats stay several days after surgery, depending on renal values, urine output and how stable they were before the procedure.
Does the device need maintenance?
Yes. The S.U.B. port is flushed and sampled periodically according to a protocol we provide, and urine is cultured to detect infection early.
Can both kidneys be treated?
Bilateral obstruction can be managed, and the surgical plan is decided case by case based on imaging and renal function.
Related services
Talk to Our Team
Send your pet's medical records and diagnostic imaging for a case review, or contact our hospital in Madrid directly.