Variations of Ureteral Ectopia in Dogs – Lessons Learned

Ectopic ureters (EU) is the most common cause of urinary incontinence in young female dogs; it is also the most common anatomic abnormality associated with incontinence of female dogs of any age. EU is recognized in cats and other large animal species (horse, alpaca etc) but is considered rare. Urinary incontinence is the most common clinical presentation of female dogs with EU. The degree of urinary incontinence is variable ranging from mild and intermittent to continuous and severe. Incontinence and may worsen in recumbent positions, with increased activity and with increased water consumption (swimming, eating snow, drug therapy i.e. steroid administration). The severity of urinary incontinence does not dictate the type and location of the ectopic ureteral orifice(s) nor has it been correlated to treatment outcomes. EU has also been diagnosed as an incidental finding in both male and female dogs with no clinical signs of urinary incontinence. Canine patients diagnosed with EU are usually, generally less than 1 year of age at the time of initial presentation. Females tend to present at a younger age than males. Although females are diagnosed more frequently than males, EU may be more common in males than historically appreciated because affected males frequently are not incontinent as a consequence of the length of urethra distal to the opening of the ectopically displaced ureters. Delayed-onset urinary incontinence has been recently reported in 5 of 22 female dogs diagnosed with congenital EU. It is likely that urinary sphincter mechanism incompetence (USMI) may play a contributing role in some female dogs presenting with delayed-onset urinary incontinence. Although EU is often viewed as a simple plumbing “bypass” problem, it is far more complex due to concurrent anatomical anomalies contributing to urinary incontinence. Recognized anomalies of the urogenital tract associated with EU include, short urethra, indistinct vesicourethral junction (VUJ) resulting in low urethral closure pressure, vaginal and vestibular abnormalities and abnormal formation of the external urethral sphincter and meatus. Abnormalities in the development of the kidney (single agenesis, renal hypoplasia and dysplasia) are encountered in some dogs with EU as well as the finding of hydronephrosis and hydroureter. EU is reported to be over represented in certain breeds of dogs including Siberian husky, Labrador retriever, Golden retriever, Soft-Coated wheaten terrier, Newfoundland, English bulldog, Welsh corgi and Poodles of any size. Related Entlebucher Mountain Dogs affected with EU have been recently described both with and without urinary incontinence. Multiple reports site the diagnosis of EU in littermates, half siblings and other related family members. At this time no specific genetic study has documented the complex genetic relationship resulting in this congenital anomaly. DNA samples are currently being collected from affected Golden retrievers and primary relatives in an effort to determine the genetic mutation. (http://www.greudna.org/). As a note of clinical interest, the Doberman pinscher, another breed over represented with juvenile urinary incontinence is not affected by EU but instead by congenital USMI. It has been reported that a specific breed diagnosed with EU can affected the prognosis and outcome of surgical treatment. All 16 Labrador retrievers diagnosed with EU in recent study regained continence after surgical repair. Bilateral displacement of the ureteral orifices has been reported to occur more frequently than unilateral. In situations of bilateral displacement, the terminal opening of each ureter may not be located at the exact same site distally. A diagnosis of bilateral disease should be made if