Introduction

Urinary tract health is vital for cats, and among the most serious conditions affecting feline urinary function is ureteral obstruction. When the ureters (tubes that carry urine from the kidneys to the bladder) become blocked, cats may suffer from kidney damage, pain, and loss of life. One advanced surgical solution to relieve this condition is Sub Ureteral Bypass (SUB) surgery. This procedure provides a reliable method to bypass the obstruction and restore normal urine flow, supporting renal health and improving quality of life.

Understanding Ureteral Obstruction in Cats

Ureteral obstruction occurs when one or both ureters are blocked by stones, strictures, or foreign material. Because cats have small ureters, even small stones can cause complete blockage.

Symptoms to Watch For

Cats with ureteral blockage may show signs such as:

• Sudden decrease or cessation of urine output

• Lethargy, inappetence

• Vomiting

• Painful abdomen (especially over the kidneys)

• Elevated creatinine and BUN on blood tests

Left untreated, ureteral obstruction can cause hydronephrosis (swelling of the kidney) and irreversible kidney damage.

Why SUB Surgery?

While conservative treatments and stenting may work in some cases, SUB surgery offers significant advantages:

• Bypasses the Obstruction: Rather than trying to clear the blockage within the narrow ureter, SUB places a catheter and connecting device to reroute urine directly to the bladder.

• Durability: SUB systems are designed to provide long-term relief with fewer complications than other interventions.

• Flexibility: The bypass works even if the original location of obstruction is unreachable or too risky to treat directly.

• Preservation of Kidney Function: By restoring urinary flow promptly, SUB helps prevent the progressive failure of the affected kidney(s).

Because SUB is a specialized surgery requiring advanced skill and equipment, it is generally performed by veterinary specialists or surgical centers.

How SUB Surgery Works

SUB surgery involves placing a bypass device that connects the renal pelvis (the part of the kidney that collects urine) to the bladder, bypassing the obstructed ureter.

Key Steps in the Procedure

1. Preoperative Assessment:
   Radiology (ultrasound, CT, or contrast studies) is used to locate the obstruction and assess kidney damage.

2. Surgical Access:
   Under anesthesia, an abdominal surgical approach is made to expose the kidney, ureter (if accessible), and bladder.

3. Placement of the SUB Device:
   A catheter and subcutaneous-access port is placed so urine from kidney drains into bladder through a new path. The native ureter remains in place but is bypassed.

4. Verification and Closure:
   Urine flow through the new path is confirmed. The port is positioned under the skin so that if flush or imaging is needed later, it can be accessed. The surgical site is closed in layers.

5. Postoperative Imaging:
   Contrast studies or fluoroscopy may be used to confirm that the bypass is working and urine is flowing properly.

The procedure is delicate and requires precision, but when successful, it offers cats a renewed lease on life.

Recovery, Aftercare, and Monitoring

Post-surgery care is essential to ensure long-term success. Owners must follow strict guidelines:

Early Recovery Phase (Weeks 1–2)

• Strict rest and restricted activity

• Pain management, antibiotics, and other supportive medications

• Monitoring for signs of leakage, infection, or complications

Intermediate Phase (Weeks 3–8)

• Gradual increase of activity under supervision

• Monitoring kidney values via blood tests

• Imaging checks to ensure the SUB remains patent

Long-Term Follow-Up

• Periodic flushing of the SUB port may be required to prevent blockage.

• Lifelong monitoring of kidney function is essential.

• Avoidance of urinary tract irritants (dietary control, hydration) helps prevent complications.

Because the SUB device is permanently implanted, regular veterinary follow-ups and imaging are critical to detect any issues early.

Risks and Possible Complications

While SUB surgery is often lifesaving, it is not without risks. Potential complications include:

• Implant obstruction or kinking

• Leakage of urine outside the bypass pathway

• Port infections or skin irritation

• Progressive kidney disease despite intervention

• Anesthetic or surgical complications

Choosing a veterinary center with experience in SUB procedures and managing post-operative care is crucial to minimize these risks.

Is SUB Surgery Right for Your Cat?

SUB is generally recommended when:

• Ureteral obstruction is confirmed and not responsive to medical therapy

• The obstruction is in a location difficult to reach with a stent

• Kidney function is still salvageable

• The cat can tolerate anesthesia and surgical stress

Your veterinary surgeon will evaluate the risks and benefits before recommending the procedure. Not all cats are candidates, but for many, SUB offers the best hope for recovery.

Conclusion

Ureteral obstruction is a serious, potentially fatal condition in cats. With Sub Ureteral Bypass (SUB) surgery, veterinarians can bypass the blockage, restore urinary flow, and protect renal function. While the procedure requires specialized skills and careful post-op management, it offers affected cats a second chance at comfort and mobility.

If your cat is facing urinary issues and discussing surgical options, British Veterinary Centre provides advanced surgical expertise, including SUB procedures, and holistic follow-up care to help your feline companion navigate recovery and maintain long-term health.