Case scenario
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.
Photo 1: Urethral prolapse in a 3-year-old non-castrated English Bulldog.
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The hematuria occurred primarily at the beginning of urination and lasted for approximately one day. Associated with the hematuria,
the owner's observed the dog excessively licking his penis. Examination of the penis and distal urethra after retraction of
the prepuce revealed prolapse of the distal urethra characterized by a red-purple, pea-sized, doughnut-shaped mass protruding
from its distal end (Photo 1).
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.
Diagnostics unveiled
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.
Biologic behavior
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.
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