How would you manage a prolapsed urethra in an English Bulldog?
A 3-year-old male non-castrated English Bulldog was admitted to the Veterinary Medical Center because of intermittent episodes of gross hematuria of two months' duration.
The prolapsed portion of the urethral mucosa was not ulcerated or inflamed. Evaluation of the intra-pelvic portion of the urethra via rectal palpation revealed that it was normal; the prostate gland was also normal. The dog's breathing was adequate at rest but became labored with mild exercise (walking). Physical examination did not reveal other abnormalities.
What is the cause of urethral prolapse?
Prolapse of the mucosal lining of the distal portion of the urethra through the external urethral orifice occurs primarily in young male dogs. Although this disorder has been encountered in several different breeds, it occurs primarily in young (mean age ~18 months; range 4 months to 5 years of age) English Bulldogs and Boston Terriers.
We have hypothesized that the predilection of brachycephalic English Bulldogs and Boston Terriers to urethral prolapse may be related to abnormal development of the urethra with superimposed increased intra-abdominal pressure as a consequence of labored breathing, dysuria or sexual activity. Increased intra-abdominal pressure could impair venous return of blood through the pudendal veins, predisposing susceptible dogs to engorgement of the corpus spongiosum surrounding the distal urethra. The observation that English Bulldogs are predisposed to congenital urethrorectal fistulas supports the hypothesis that maldevelopment of the urethra may be involved. Increased intra-abdominal pressure secondary to stertorous breathing caused by stenotic nares and abnormal elongation of the soft palate may impair venous return from the penis. Detection of urocystoliths and vesicourachal diverticula in some affected dogs suggests that increased intra-abdominal pressure secondary to dysuria may also be a predisposing factor. The observation that urethral prolapse is more severe when male dogs are sexually active may be linked to distension of submucosal vascular channels located in the penis.
What other diagnostic procedures would you recommend?
The dog could urinate normally. However, results of analysis of a voided urine sample revealed numerous red cells, a few white cells, moderate proteinuria and a specific gravity of 1.035. Evaluation of a urine sample collected by cystocentesis following collection of the voided urine sample revealed two to three red cells per high power magnification (450X), a trace of protein, and a urine specific gravity of 1.032. Aerobic culture of both urine samples for bacteria revealed no growth. Evaluation of prostatic fluid collected during manually induced ejaculation revealed no abnormalities.
Evaluation of a CBC was normal. Evaluation of a contrast urethrocystogram, and double-contrast cytogram revealed no anatomic abnormalities.
Although not applicable to this case, if the prolapsed portion of the urethra is to be surgically removed, it should be placed in formalin (or other suitable tissue fixative) for examination by light microscopy. Lack of deep-seated inflammation and scarring may suggest that recurrence is less likely.
In contrast, mucosal ulceration, extensive inflammation, necrosis and scarring may indicate that problems are more likely to recur.
What is the biologic behavior of a prolapsed urethra?
The biologic behavior of untreated urethral prolapses has not been evaluated in a large number of cases. This may be related to the fact that most textbooks recommend some form of surgery to treat prolapsed urethras. Cases reported in the literature have typically been managed by manual reduction of the prolapse combined with a purse-string suture, or surgical excision of the prolapsed portion of the urethra.
What types of management would you consider?
If our hypothesis is valid that increased intra-abdominal pressure is a risk factor for urethral prolapse in dogs predisposed to this abnormality, consideration should be given to minimizing problems that cause increases in intra-abdominal pressure.
This may include eliminating underlying causes of dysuria, castration to minimize sexual activity, and correction of stenotic nares and/or elongated soft palates. We emphasize that these recommendations have not been validated by controlled clinical trials.
In situations (as described in this case) where prolapse of the urethra is asymptomatic, or when episodic bleeding is no more than an inconvenience, therapy may not be required. We do not recommend use of glucocorticoids, since they are unlikely to provide any beneficial effect, but are likely to increase the risk for ascending urinary tract infection. If excessive licking contributes to trauma of the prolapsed urethra, Elizabethan collars or similar types of restraint devices may help to break the licking cycle.
If prolapse of the urethra occurs only during erections, consider castration prior to attempting surgical correction. Low doses of diethylstilbestrol given for approximately one month following castration may aid in the reduction of the frequency of erections.
If the urethral prolapse is small, and if further treatment is deemed unnecessary, manual reduction may be considered. Manual reduction of the prolapsed segment is facilitated by use of general anesthesia and a urinary catheter. The catheter should be as large as it can be without causing further damage to the urethra. Alternatively, a Swan-Ganz balloon catheter or a pediatric Foley catheter may be of value in reducing the prolapse. Following correction of the problem, a purse-string suture of non-absorbable monofilament material should be placed at the external urethral orifice. The urinary catheter should then be removed. The purse string suture should be removed in approximately five days. Appropriate antibiotics should be given if bacterial urethritis is a cause or result of the prolapse. The owners should be advised that the urethral prolapse might recur, especially if an underlying predisposing cause has not been identified and eliminated or controlled.
Surgery should be considered for patients with excessive bleeding, pain or extensive ulceration and/or necrosis of the prolapsed tissue. The most commonly recommended type of surgery involves removal of the prolapsed urethral tissue, and suturing of viable urethral mucosa to the external surface of the penis. Two procedures designed to resect the prolapsed portion of the urethra have been described. The primary difference between these procedures is the method used to prevent retraction of the urethral mucosa into the penis after the prolapse is amputated. In one technique, two straight intestinal surgical needles are inserted at right angles to each other, first through the external surface of the penis, then through the non-prolapsed portion of the distal urethral lumen, and finally through the external surface of penis of the opposite side. The prolapsed portion of the urethra is then excised and the remaining edge of the viable urethra is sutured to the external surface of the penis using a simple interrupted pattern (4-0 to 6-0 Monocryl absorbable monofilament suture).
In the other procedure, stay sutures are placed in the mucosa of the prolapsed portion of the urethra to facilitate manipulation. After inserting a sterile catheter into the urethral lumen, an incision is made approximately 0.5 cm caudal to the prolapsed portion of the urethra and completely encircling the penis. The initial incision is carried down to the urethral mucosa. After dissecting penile tissue away from the urethral mucosa, the ventral portion of the mucosa is incised halfway around its circumference. By incising only half the urethral circumference, stay sutures are not required to prevent the mucosa from retracting back into the penis.
After ventral portions of the urethral mucosa are sutured to the external surface of the penis with 5-0 to 6-0 Monocryl absorbable suture, the remaining portion of the urethra is excised and reunited with the penis. A "purse-string" effect can be prevented by using care not to pull the suture material too tight during closure.
Laser surgery may reduce hemorrhage during amputation of the prolapsed urethral mucosa, and thereby improve visualization of the operative site. It may also reduce post-operative pain and swelling. An Elizabethan collar may be used to prevent licking-induced trauma to the anastomosis site.
Appropriate antibiotics should be given if urethritis is associated with the prolapse. Varying degrees of hematuria, especially during micturition, often occur for approximately one week following surgery.
What type of therapy was selected for the 3-year-old Bulldog?
Because of significant respiratory difficulties associated with stenotic nares and an elongated soft palate, and because of the episodic occurrence of hematuria, the owner elected a wait and watch therapeutic strategy of benign neglect. During a four-year span from the date of diagnosis, the urethral prolapse was not associated with any clinical signs. It did not change in size, shape or color. Unfortunately the dog died of dilated cardiomyopathy, ending our opportunity to further evaluate this disorder.
Dr. Osborne, a diplomate of the American College of Veterinary Internal Medicine, is professor of medicine in the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Minnesota.