Perineal Urethrostomy Surgery in Cats

By Catherine Barnette, DVM

What is perineal urethrostomy surgery?

A perineal urethrostomy (sometimes referred to as a PU) is a surgical procedure that is most commonly performed on male cats with a urinary obstruction. This procedure removes the narrowest part of the urethra (the tube that transports the urine from the bladder to the exterior of the body), allowing easier urination with a lower risk of reobstruction.

Male cats develop urinary obstructions much more readily than female cats, due to differences in urinary tract anatomy between the two sexes. While the female urethra is relatively short and maintains a consistent diameter as it travels from the bladder to its external opening, the male urethra differs in that it is slightly longer and, more importantly, it narrows as it enters the penis. This narrowing of the urethra predisposes males to urinary obstructions, in which the urethra becomes blocked with stones, blood clots, mucus, or tumors. A perineal urethrostomy creates a new urinary opening that decreases the length of the urethra and allows urine to bypass this narrowed region. This surgery can decrease the likelihood of recurring obstruction.

Less commonly, perineal urethrostomy may also be performed in cats with severe urethral trauma. By allowing urine to exit the body before it reaches the damaged part of the urinary tract (for example, in the case of traumatic injury to the penis), your veterinarian can ensure that complications such as scar tissue or infection do not cause a urinary obstruction for your cat.


When is perineal urethrostomy surgery recommended?

Perineal urethrostomy surgery is most commonly recommended in the following situations.

  • A urethral obstruction within the penis that cannot be removed through medical therapy. Typically, urethral obstructions are dislodged by the passage of a urinary catheter. This catheter is advanced through the external opening of the urethra towards the bladder; any stones or mucus that are present within the urethra are flushed into the bladder, where they can be addressed using medication or surgery. In the case of an obstruction that cannot be alleviated with a catheter, perineal urethrostomy may be required to re-establish urine flow and allow the cat to urinate.
  • Recurrent urethral obstructions. In some male cats, urinary obstructions may become a frequent occurrence. Even if these cats can be unblocked, cats who frequently reobstruct may benefit from a perineal urethrostomy to decrease the likelihood of future obstructions.


How is a perineal urethrostomy surgery performed?

Your cat will undergo a pre-surgical examination, as well as pre-anesthetic blood testing prior to anesthesia. This pre-surgical evaluation will allow your veterinarian to assess your cat’s health status and ensure that he is a good candidate for anesthesia.

"If your cat is currently obstructed, he will be stabilized prior to surgery."

If your cat is currently obstructed, he will be stabilized prior to surgery. This stabilization will involve administering intravenous fluids to correct dehydration and electrolyte abnormalities. Pre-surgical stabilization will make your cat a better candidate for anesthesia and decrease the likelihood of complications.

Following the pre-surgical evaluation, your cat will be administered medications and placed under general anesthesia. The surgical site will be prepared, shaving the hair from the area and using surgical scrub to remove bacteria from the surface of the skin in order to prevent infection. The surgeon will then perform the perineal urethrostomy by removing the penis and suturing the deeper, larger-diameter region of the urethra to the skin to create a new urinary opening.

What after-care is required following a perineal urethrostomy?

After surgery, your cat will be required to wear an Elizabethan collar (e-collar) to prevent self-trauma to the surgical site. Excessive licking can interfere with healing, leading to infection and scar tissue formation.

Your cat will also need to be kept calm and have his activity restricted. Your veterinarian may recommend confining your cat to a small area, away from other pets, where his activity can be limited and he can be closely monitored.

What are the expected outcomes after a perineal urethrostomy?

With appropriate pre-surgical stabilization, surgical technique, and aftercare, the prognosis for patients with perineal urethrostomy is good. Occasionally, a stone may form that is too large to pass through the urethrostomy opening; however, this is uncommon and most cats do not reobstruct after a perineal urethrostomy.