Ectopic ureter in dogs: urine leakage and treatment

Overview

A ureter carries urine from a kidney to the bladder. In ectopia, its opening lies further back than usual. Urine may pass directly into the urethra or, in females, the vagina. The abnormal opening may bypass the sphincter mechanism needed for continence.

One or both ureters may be affected. Abnormal openings of both ureters have been described in about 25% of cases. Reported prevalence in dogs is 0.016–0.045%. However, the condition may involve more than urine leakage, as kidney or other urinary tract abnormalities can occur alongside it.

Some dogs remain continent despite the abnormal structure. A dilated ureter or renal pelvis may then be found incidentally.

Causes

The defect arises during urinary tract development before birth. An intramural ureter joins the bladder but continues too far beneath its lining within the wall. It then opens in the wrong place near the bladder neck or further back. More than 95% of canine ectopic ureters run within the wall.

An extramural ureter runs outside the bladder wall and bypasses the bladder. Apart from its course, the abnormal opening may lie inside or outside the bladder. One ureter can also have several openings. Sometimes an extra branch continues backwards from a ureter that drains normally into the bladder.

Normal ureteral openings lie at the front of the bladder's trigone. A normal ureter runs only a short distance beneath the lining before opening into the bladder. The urethral sphincter mechanism contains both smooth and striated muscle.

Risk factors

The abnormality is most often diagnosed at 3–6 months of age. Females are diagnosed more often than males. This may partly reflect easier recognition of incontinence in females. Symptoms in males may start only in adulthood.

The condition occurs more often in Labrador Retrievers, Golden Retrievers and Siberian Huskies, for example. Entlebucher Mountain Dogs, Miniature and Toy Poodles, and West Highland White Terriers are also predisposed. The developmental disorder has an inherited basis. Adult age alone therefore does not rule out a congenital cause of incontinence.

In a male case series, median age at incontinence onset was 6.5 months, ranging from 1.5 months to 7 years.

Typical symptoms

At home, you may notice:

• Involuntary urine dribbling or leakage.

• A puppy failing to stay dry despite house training.

• Wet bedding after sleep or rest.

• Leakage during movement or play.

• Recurrent urinary tract infections.

• Urine-related irritation around the vulva.

Dribbling may be constant or intermittent. Your dog may nevertheless pass a normal stream outdoors. Normal urination therefore does not remove the need to investigate involuntary leakage. A concurrent urinary tract infection may cause more frequent urination.

Urinary infection can also cause blood in the urine. Urination may become painful.

Constant urine irritation can also inflame the vaginal lining.

Complications and consequences

The same dog may have renal dysplasia, a developmental kidney disorder. The renal pelvis may become markedly dilated, called hydronephrosis. A dilated ureter is called a hydroureter. The ureter's lower end may form a cystic dilation, or ureterocoele.

Urethral sphincter mechanism weakness occurs in an estimated 47–67% of females with ectopic ureters. This may explain persistent incontinence after successful structural correction. Urine may leak into the abdomen after surgery. The repaired site may also narrow. Urinary tract infection can develop after correction too.

Among females, 47–72% have become continent after endoscopic ablation alone. Medication or other additional treatment has increased continence rates to 77–82%. Of 14 incontinent males, 11, or 79%, became completely continent with laser treatment alone. Median follow-up in males was 1,789 days, ranging from 98–3,560 days.

Renal pelvic dilation has also been found in continent males. These dogs have also had narrowing of the ureteral opening.

An artificial sphincter may cause urethral narrowing requiring device removal. Bacterial biofilm on a surgical implant can increase infection risk.

Diagnosis at the vet

History and investigating other causes

The vet establishes whether leakage is involuntary or the dog is consciously urinating in an inappropriate place. Age at onset helps assess a congenital defect. Timing during rest or activity also guides investigation. Observing the urine stream or a video of it forms part of initial assessment.

Bladder size is assessed before and after urination. A large residual volume suggests a bladder emptying problem. Residual urine should be measured within 10 minutes of urination. A male may need several relaxed attempts to urinate before assessment.

Urinalysis and bacterial culture are part of investigating incontinence. A sample suggesting infection may also undergo susceptibility testing when needed. Blood tests may include cell counts and biochemistry to assess organ function. General examination also assesses external genital structure.

In females, vulval skin inflammation and folds are checked too. Neurological examination assesses findings including gait and back pain. This also looks for neurological causes of urinary dysfunction. Ultrasound can assess residual urine without placing a catheter.

Imaging and endoscopy

Ultrasound helps assess kidney structure and ureteral dilation. It can also track urine jets from the ureters into the bladder. Reported sensitivity compared with cystoscopy has been 87.8–93.6%. Specificity, the proportion of normal structures correctly identified, has been 86.2–100%.

Ultrasound does not expose your dog to ionising radiation.

Ultrasound does not completely rule out an ectopic ureter when symptoms are suggestive. Examiner experience affects diagnostic success. Movement may make urine jets difficult to locate, so light sedation is often needed. An absent jet alone may also have a technical explanation.

Contrast-enhanced CT shows urinary tract structures in three dimensions. Kidney function is assessed before intravenous contrast. CT is performed under sedation or general anaesthesia. However, it does not always distinguish every abnormal branch or opening.

Cystoscopy examines the bladder and urethra with an endoscope under general anaesthesia. It shows openings and abnormal mucosal areas in detail. Imaging is still needed to assess the kidneys and upper urinary tract. Very small size may limit endoscopy.

Not every ectopic ureter investigation needs CT. During endoscopy, the true opening must be distinguished from extra side openings.

Treatment

Correcting the abnormal opening

The vet chooses correction according to the ureter's course. Medication does not correct its abnormal opening. Endoscopic ablation is the first-choice treatment for an intramural ureter. The abnormal wall is opened so urine enters the bladder at the correct point.

Correction can use a laser or electrocautery. Diagnosis and treatment can often take place during the same anaesthetic. An extramural ureter is instead surgically repositioned to open into the bladder. Removal of a severely damaged kidney and ureter is considered only if the other kidney functions normally.

In some cases, fluoroscopy is combined with endoscopy to confirm the course. A ureteral catheter may help identify the correct route and improve safety. If the new opening remains outside the bladder, leakage may continue.

Mean procedure duration in males was 82 minutes, ranging from 47–182 minutes. This included diagnostic endoscopy, creation of a perineal access route and laser ablation itself.

Persistent leakage and follow-up

Persistent sphincter weakness may be treated with medicines supporting its function. In severe cases, urethral bulking injections may be considered. An adjustable artificial urethral sphincter is another possible additional treatment. Urine samples and cultures are monitored repeatedly after correction.

After open abdominal correction, exercise is usually restricted for 2 weeks. Normal movement may resume sooner after endoscopic correction. Mild pain on urination may occur for 1–3 days after endoscopy. Slight blood in the urine from mucosal irritation may occur during the same period.

Some dogs need overnight hospital monitoring after the procedure.

Available ultrasound reviews in the male case series took place at least 6 weeks after treatment. Renal pelvic dilation decreased in 10 of 14 kidneys during male follow-up. Of the dilated ureters, 12/17 decreased in size. However, dilation may not disappear completely even after successful decompression.

Prevention

A congenital ureteral abnormality is present at birth. Ultrasound screening of breeding dogs has shown benefit in a susceptible Entlebucher Mountain Dog population. Excluding dogs from breeding because of an opening outside the bladder or suggestive symptoms reduced the defect in later generations. As some dogs have no symptoms, continence alone does not establish normal urinary anatomy.

Urine is tested before corrective urinary procedures to assess infection risk. Antibiotics are chosen according to culture and susceptibility results when needed.

An asymptomatic bacterial finding does not usually require antibiotics. However, the period before a urinary tract procedure is an exception.

Important for dog owners

Record when urine leaks and what your dog is doing at the time. A video of normal urination can help the vet assess it. Mention whether dribbling occurred before castration or spaying. Describe whether your dog can empty its bladder with a normal stream too.

After correction, monitor leakage separately from the ability to urinate. An open surgical wound needs care alongside restricted exercise. Repeated dribbling after correction may need additional sphincter treatment. Urine sample checks remain part of follow-up after structural correction.

Frequently asked questions

Can a puppy urinate normally despite an ectopic ureter?

Yes, particularly if only one ureter opens abnormally. Your dog may pass a normal stream outdoors and still dribble involuntarily. Persistent wetness at rest or during movement is therefore an important part of the history.

Is ultrasound enough for diagnosis?

Ultrasound is useful for assessing kidneys and the rest of the urinary tract. However, it cannot rule out every ectopic ureter. Endoscopy shows ureteral openings more precisely than other methods. An intramural ureter can be corrected with a laser at the same time.

Can medication correct the abnormal opening?

Medication does not change the ureter's congenital course. Structural correction uses endoscopy or surgery according to the route. Nevertheless, medication may help concurrent sphincter weakness after correction. Additional treatment may also include an adjustable artificial sphincter.

Does correction always make a dog completely continent?

Not every dog becomes continent with structural correction alone. In females, continence after endoscopic ablation has been 47–72% without additional care. Sphincter treatment and other procedures have improved results. Leakage and possible further treatment are therefore assessed afterwards.

Can the defect be found in a dog that does not dribble?

Yes, some ectopic ureters are symptom-free or cause symptoms only in adulthood. A dilated ureter or renal pelvis may then be the first finding. Such a dog's upper urinary tract also needs imaging assessment.