Perineal Urethrostomy Surgery in Cats

By Malcolm Weir, DVM, MSc, MPH; 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 along with a lower risk of re-obstruction.

"This surgery can decrease the likelihood of recurring obstruction."

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 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 by 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 be performed on 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. Usually, urethral obstructions are dislodged by the passage of a urinary catheter. This catheter is advanced through the tip of the penis 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 relieved 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 become a frequent occurrence. Even if these cats can be unblocked, they may benefit from a perineal urethrostomy to decrease the likelihood of future obstructions (i.e., create a bigger hole for them to urinate out of).

How is perineal urethrostomy surgery performed?

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

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.

After the pre-surgical evaluation, your cat will be given medication and placed under general anesthesia. The veterinary team will prepare the surgical site, shave the hair from the area, and use a surgical scrub to remove bacteria from the skin and 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 restricted activity. Your veterinarian may recommend confining your cat to a small area, away from other pets, where their activity can be limited and they 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 re-obstruct after a perineal urethrostomy.

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