Ectopic Ureter in Cats
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. In cats affected with ectopic ureter, the ureter completely bypasses the bladder and enters the urethra from outside of the bladder walls (extramural type).
This condition is rare, and when it does occur it may be asymptomatic, with no apparent urination problems. When symptoms are apparent, they often present as occasional or continuous incontinence, and inflammation of the vagina (vaginitis) from urine scalding the vaginal tissue.
Ectopic ureter has an unknown mode of inheritance, but there does appear to be a component of breed predisposition.
Your veterinarian will use a diagnostic technique called urethrocystoscopy, which uses an insertable tube with an attached camera. In this way, your doctor will be able to examine the bladder internally, and visualization of the urethral opening into the urethra or vagina will be more apparent. 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 radiography. 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.