What is a Perineal Urethrostomy (PU) for Cats?
A urethrostomy is a surgical procedure that creates an opening in the cat’s urethra, the tube that carries urine from the bladder. The procedure is done to correct obstruction to urine flow, a life-threatening condition. Even partial obstruction to urine flow can lead to serious complications such as urinary tract infection and loss of bladder tone. A urethrostomy relives obstructions caused by protein plugs, stones, trauma, or scarring. A temporary opening that is later allowed to close is called a urethrotomy. A permanent opening is called a urethrostomy. In cats the procedure is almost always done in the perineum (between the rectum and scrotum), and the procedure is termed “perineal urethrostomy” and often abbreviated and referred to by the letters “PU”.
What Are the Indications for Performing a Perineal Urethrostomy on a Cat?
Urethrostomy is indicated when the urethral opening is too narrow or persistently obstructed. This procedure is most often used in male cats with feline urologic syndrome prone to urethral obstruction from protein plugs, bladder “sand”, or bladder stones that enter the urethra and obstruct urine flow. While some cats with these problems respond to diet and medication, others experience recurrent episodes of urinary obstruction. In these cats, surgery is the best treatment. Urethrostomy also is indicated in cases of severe penile trauma or scarring that does not allow for normal passage of urine.
What Preoperative Tests Are Needed Before a Perineal Urethrostomy?
Preoperative tests depend in part on the age and general health of the animal as well as the cause for the urethrostomy. If treatment for urinary obstruction is the cause, a packed cell volume (or complete blood count) should be determined and a serum biochemical profile test done to assess the kidney function and blood potassium. Often an abdominal x-ray or ultrasound of the bladder will be recorded. If the need for urethrostomy is related to major trauma to the area, more extensive tests such as radiographs (x-rays), blood count, serum biochemical tests, a urinalysis, and possibly an EKG may be necessary. Creation of the urethrostomy may even be delayed until the animal is stabilized.
What Type of Anesthesia is Needed For a PU?
As in human patients, the procedure in cats requires general anesthesia to induce complete unconsciousness, relaxation, and relief of pain. In the usual case, the pet receives a pre-anesthetic sedative-analgesic drug to help him relax, a brief intravenous anesthetic to allow placement of a breathing tube in the windpipe, and inhalation (gas) anesthesia in oxygen during the actual surgery.
How Is the PU Surgery Done on a Cat?
Following anesthesia, the pet is placed on a surgical table, typically lying on his abdomen with the perineum exposed to the surgeon. The hair is clipped around the area selected for the surgery. The surgery is done typically between the scrotum and the rectum. After clipping, the skin is scrubbed with surgical soap to disinfect the area. A sterile drape is placed over the surgical site, and a scalpel is used to incise the skin. Your veterinarian will have to dissect surrounding tissues until the urethra is exposed, and then will make an incision in the urethra and the penis. The surgeon will suture the edges of the urethra to the edges of the skin incision to create a wide urethral opening. Some surgeons choose to use absorbable sutures (stitches) that dissolve over time. Other surgeons use non-absorbable sutures that need to be removed in about 10 to 14 days. When the procedure is done to intact tomcats, castration is usually performed as the same time. That procedure is explained elsewhere on this site.
How Long Does the Perineal Urethrostomy Procedure Take?
The procedure takes about 45 minutes to an hour in most cases, including the needed time for preparation and anesthesia. In cases of severe trauma or scarring, the procedure can take longer and may require two surgeons or referral to a board-certified surgical specialist.
What Are the Risks and Complications of a PU Surgery for a Cat?
The overall risk of this procedure in a healthy cat is very low. The major risks are those of general anesthesia, bleeding (hemorrhage), post-operative infection, and wound breakdown (dehiscence) over the incision. Scar formation occurs in some cats and leads to closing off the urethra. While the overall complication rate is low, a serious complication can result in death or the need for additional surgery.