The cat with LUTD – a surgeon’s perspective
The medical management of feline LUTD has evolved considerably over the last 15 to 20 years with considerable progress in the understanding of dietary influences and manipulation, and increased awareness of both clinicians and owners resulting in earlier recognition of problems and meticulous management of affected cats. Consequently, the role of surgery in the management of cats with LUTD has changed. While most clinicians, both internists and surgeons would agree that surgery is not a first line of defence, there are times when surgical intervention is indicated or chosen to facilitate the management of affected cats. Having a clear perspective of when it is indicated will only enhance the outcome for the cat and satisfaction of the client.
What surgical procedures are indicated?
There are three surgical procedures that are used in the management of LUTD. By far, the most important procedure that a clinician should be familiar with, should not hesitate to perform, and the only procedure that is required in an emergency, is the tube cystostomy. This procedure requires surgical placement of a tube through the ventral body wall into the urinary bladder (1). This procedure is best performed on the anaesthetised animal, albeit a short procedure, but can be performed under sedation and local aneasthesia if necessary. Percutaneous techniques with specialized catheters are described for dogs. Placement of a tube cystostomy allows relief of outflow obstruction and subsequent stabilization of the animal, maintains decompression of an overdistended urinary bladder allowing the detrussor muscle to recover, allows the urethra to recover from inflammation and trauma induced by the disease or attempts at catheterization, and since connected to a closed collection system, facilitates the monitoring of urine output and renal recovery. A tube cystostomy obviates any need for an indwelling catheter which can further irritate the urethra, if it can be passed at all. Any indwelling catheter, if left open, increases the risk of environmental contamination of the catheter and makes urine quantification impossible.
The other procedures used in the management of LUTD are perineal urethrostomy (Figure 1) and antepubic urethrostomy. Perineal urethrostomy makes a urethral stoma at the perineum, in the membraneous urethra (2,3). The antepubic urethrostomy makes a urethral stoma in the ventral body wall and is clearly a salvage procedure (4). It is indicated when there is irreparable damage to the distal membranous urethra, often from repeated catheterization attempts, that make perineal urethrostomy impossible. Late stricture formation which is not resectable may also be an indication (Figure 2). A modification of the procedures has been described, creating a transpelvic stoma (5). The indications for this procedure are the same as for the other urethrostomies. The indications for perineal urethrostomy are sometimes clear and sometimes controversial. Clearly, it is indicated when there is irreparable damage to the penile urethra. Of more concern is the quest to perform the procedure when the obstruction cannot be relieved. Perineal urethrostomy is not an emergency procedure. When the obstruction cannot easily be relieved, tube cystostomy is indicated. Once the animal is stabilized, and the urethra has time to recover, more controlled attempts can be made at relieving the obstruction. Of question is the indication to perform perineal urethrostomy in the cat that has repeated episodes of obstruction despite meticulous and dedicated medical management. The decision to perform a perineal urethrostomy in such a cat must be an informed decision by the client. Since there is no crystal ball to predict if the cat will ever obstruct again, and hindsight will be 20-20, a certain decision is not possible in such a case. Whether the success of the procedure is because the cat was never going to obstruct again, or because the procedure prevents obstruction, will not be known.
What are the consequences of urethrostomy?
The anatomic changes associated with perineal urethrostomy include shortening the length of the urethra by removing the penile urethra, probably by slightly less than a third. The new stoma is created in the larger diameter membranous urethra at the level of the bulbourethral glands. The proposed consequence of this change is loss of the natural defense mechanisms normally provided by the narrow penile urethra, primarily preventing ascending contamination. The first occurrence of urethral obstruction of cats with LUTD is usually not associated with bacterial infection (6-8). Bacterial infection is more likely after manipulation including intermittent or indwelling catheterization, and repeated obstruction. Interestingly, cats with LUTD with bacterial infection undergoing perineal urethrostomy have a recurrence of urinary tract infection while healthy cats undergoing perineal urethrostomy for other reasons do not develop urinary tract infections (9,10). Whether recurrence in cats with LUTD is any different to what might occur without surgical intervention is unknown. Thus, perineal urethrostomy does not put a cat at risk for urinary tract infection unless the cat has a previous history of recurrent bacterial urinary tract infections with LUTD.
An antepubic urethrostomy causes similar anatomical changes, albeit shortening the urethral length even more. The physical location of the stoma on the ventral abdomen may increase the risk of ascending contamination. Urine scalding can be a problem also. Urinary incontinence may be a problem although the vesicourethral junction should not be affected. In one study of 16 cats, 13 of which have LUTD, recurrent bacterial urinary tract infections in five and signs of LUTD occurred in eight (4). No cats undergoing antepubic urethrostomy for trauma developed bacterial urinary tract infections, concurring with the results seen with perineal urethrostomy.
What are the complications of perineal urethrostomy?
Bleeding from cut penile tissue is the most frequent early complication. This resolves without intervention. The most common long-term complication is stricture associated with improper surgical technique, indwelling catheterization and self-trauma. Surgery is best performed by an experienced individual. Indwelling catheterization is not indicated. If urinary bladder decompression or urethral diversion is necessary, a tube cystostomy should be considered. Efforts to reduce self-trauma are imperative.
Every effort should be made to provide meticulous medical management and preventative strategies for cats with LUTD. The ability to perform a tube cystostomy is an important management tool, especially in an emergency. The indication for urethrostomy in the face of irreparable urethral trauma are obvious. Perineal urethrostomy alone is not indicated in the treatment of LUTD. The decision to perform perineal urethrostomy in cats with repeated obstruction despite meticulous medical management must be an informed decision made on a case-by-case basis.
This article was kindly provided by Royal Canin, makers of a range of both wet and dry urinary diets for cats and dogs, for the full range please visit www.RoyalCanin.co.uk or speak to your Veterinary Business Manager:
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