Urethral Shaft Abnormality in Dogs
Ectopic Ureter in Dogs
An ectopic (displaced) ureter is a congenital abnormality in which one or both ureters open into the urethra or vagina. Bilateral ectopia affects both ureters, and unilateral ectopia affects one ureter. Dogs affected with ectopic ureter will have the tubular shaft bypass the bladder floor (trigone) and enter through the bladder wall. Less frequently, the ureter opens into the bladder floor and continues as a trough into the urethra.
The following dog breeds may be predisposed to displaced ureter: Labrador Retriever, Golden retriever, Siberian husky, Newfoundland, Bulldog, West Highland White Terrier, Fox Terrier, and Miniature and Toy Poodles.
Symptoms
This condition is rare, especially in male dogs. Occasionally, a dog with this abnormality may be asymptomatic and show no apparent urination problems. However, some common symptoms to look out for include occasional or continuous incontinence, and inflammation of the vagina (vaginitis) from urine scalding the vaginal tissue.
Causes
Ectopic ureter has an unknown mode of inheritance, but there does appear to be a component of breed predisposition.
Diagnosis
Your veterinarian will use a diagnostic technique called urethrocystoscopy, which uses an insertable tube with an attached camera. In this way, the veterinarian will be able to examine the dog's bladder internally, and visualize the opening into the urethra or vagina. Your veterinarian will also be looking to identify holes (perforations) in the structure of the urethra (urethral fenestrations), depressions, striping (or streaking), and tenting in the bladder.
When this diagnostic method is performed skillfully, a more accurate diagnosis can be made than with external imaging techniques, such as X-rays. Another technique, urethral pressure profilometry, measures surface variations to detect coexistent urethral muscle (sphincter) incompetence. There remains the possibility that a displaced ureter will confound the results of this test, however.
Treatment
Treatment for repairing an ectopic ureter will involve surgically creating a new ureteral opening into the bladder, or removing a blocked or severely infected kidney. A portion of the displaced ureter will need to be removed, if feasible, and the ureter opening (ureterocele) into the bladder then repaired.
Incontinence may continue if your dog also has urethral muscle incompetence, and will be weakened to some degree during recovery from surgery. Some puppies with urethral muscle incompetence are able to control urination after their first heat cycle. Additionally, incontinent dogs should not be spayed before their first heat.
Living and Management
Your veterinarian will need to evaluate the effectiveness of the surgery in a follow-up visit. Internal imaging of the dog's urinary organs and bladder using dye injection through the vaginal canal (for females) will follow the track of the fluid and will make it possible to visually inspect the healing of the surgical site. Surgically elevating the vagina to support the bladder neck (where the urethra and bladder join) using the colposuspension technique may correct the incontinence.
If incontinence persists, phenylpropanolamine, an alpha-blocker, may be prescribed to enhance urinary flow, or to relieve tension and pain, a tricyclic antidepressor agent such as imipramine can be prescribed. Reproductive chemical hormone therapy may increase the naturally occurring sensitivity of urethral stress response receptors. The nonsteroidal estrogen Diethylstilbestrol, meanwhile, is administered orally to spayed bitches for urethral muscle control. In some females, a combination of estrogen therapy and phenylpropanolamine, for controlling incontinence, may be more effective.
In incontinent male dogs, steroid therapy may be prescribed. Testosterone propionate is administered initially to see if replacement therapy will be effective. For longer action, testosterone cypionate is used.
Reproductive hormone therapy is not advised in immature animals.
