Perineal Urethrostomy

Male cats are particularly prone to urethral obstruction, a condition in which the urethra—the tube carrying urine from the bladder through the penis—becomes blocked. Most obstructions are caused by plugs made of inflammatory debris, mucus, crystals, or small stones (calculi) that often originate in the kidneys and migrate into the bladder and urethra.

The exact mechanism behind inflammation and stone formation is not fully understood. Diet and viral infections are suspected contributors, while other documented causes include neoplasia, trauma, and scarring from previous injury. Importantly, early neutering does not reduce urethral diameter in cats.

Most affected cats are between 1 and 10 years old. Clinical signs range from mild to severe. Early signs resemble lower urinary tract inflammation and include:

• straining to urinate
• frequent attempts to urinate
• blood in the urine
• painful urination
• urination outside the litter box

These episodes may resolve spontaneously within 5–7 days, but recurrence is common within 6–12 months.

If complete obstruction develops, the condition becomes life-threatening. Cats may repeatedly enter the litter box without producing urine, vocalize in pain, become restless or withdrawn, stop eating, and become lethargic. Death can occur within 3–6 days if the obstruction is not relieved. On physical examination, the bladder is typically markedly enlarged and painful unless rupture has occurred.

Identified risk factors for feline lower urinary tract disease include dry-food diets, indoor confinement, stress, fearful or aggressive temperament, and multi-cat households. Obstructions are reported more frequently during winter months. Inflammatory bladder disease with mucus plug formation (historically termed Feline Urologic Syndrome) is more common in males. Congenital bladder outpouchings (vesicourachal diverticula) may predispose to infection or result from chronic inflammation.

Blood tests are used to assess kidney function and identify systemic illness. Urinalysis evaluates for crystals and may be submitted for culture, although bacterial cystitis is uncommon in cats.

In recurrent cases, abdominal radiographs are obtained to identify bladder or kidney stones. Contrast studies of the bladder and urethra may be performed to detect structural abnormalities such as urethral strictures or bladder wall defects.

Urethral obstruction is an emergency. Most cats require sedation or general anesthesia to allow placement of a urinary catheter. The obstruction is flushed out or pushed back into the bladder, which is then thoroughly irrigated to remove sediment.

The catheter is typically left in place for several days to allow urethral swelling to subside. After removal, the cat must demonstrate normal urination before discharge. Adjunctive treatment may include pain control, dietary modification to reduce crystal formation, and medications to decrease urethral spasm and stress.

If bladder stones are present and cannot be managed medically, cystotomy (surgical opening of the bladder) is performed. This is also indicated for congenital bladder diverticula.

Cats with recurrent or unresolvable obstructions, despite appropriate medical management and without correctable underlying disease, may require perineal urethrostomy (PU). This surgery permanently widens the urethral opening, allowing mucus plugs, crystals, and small stones to pass and reducing the risk of future obstruction.

After surgery, paper or pelleted litter is recommended temporarily. Some cats may need a urinary catheter for 2–3 days if swelling or urine leakage under the skin occurs. An Elizabethan collar is essential for 10–14 days to prevent self-trauma. Skin sutures may be absorbable or require removal, depending on technique.

Potential postoperative complications include bleeding, swelling, infection, and urethral stricture due to scarring—often associated with licking, urine leakage, or incomplete surgical dissection. Approximately 25% of cats develop bacterial urinary tract infections within the first year after PU.

While PU effectively prevents life-threatening urethral obstruction when performed correctly, it does not prevent bladder inflammation or stone formation. Some cats may continue to show signs of lower urinary tract disease, but the risk of fatal obstruction is markedly reduced.