Diagnosis
The tests performed to evaluate a pet with incontinence depend upon the age of the pet and on the presence or absence of other signs. It is common to collect a urine sample for bacterial culture and to see if the urine is dilute or shows evidence of an infection. Infections of the urine may be secondary to another cause of incontinence.
To diagnose this condition a dye study of the bladder is usually performed. Sometimes the abnormal opening into the vagina can be seen during a careful examination under anesthesia using special equipment.
Most puppies with ectopic ureter(s) also have a bladder infection that will improve with antibiotics but the infection will return until the problem is corrected.
In some cases the ureter can be surgically moved back to the normal location in the bladder and incontinence may resolve. In other cases, long standing infection of the kidney may have damaged the kidney requiring the removal of one kidney. In yet other cases the abnormality of the ureter can be corrected but the pet remains incontinent, probably due to the presence of other birth defects in the urinary system.
A bladder infection can cause either a strong urge to urinate or if the bladder infection is long standing it can cause scarring of the bladder preventing it from stretching to hold urine. In this case the pet is usually not truly incontinent in that they know they are urinating, but they have such a strong urge to empty their bladder that they may urinate in abnormal locations or urinate very frequently. It is common to evaluate incontinent pets for the presence of a bladder infection.
Pets with a partial blockage of the urethra with a stone or a tumor may show incontinence. If they cannot empty their bladder completely because something is blocking the path to the outside, the bladder may get so large that the back pressure of urine in the bladder actually forces some urine to leak around the blockage. In these pets the enlarged bladder can be felt on examination. Total blockage of urine flow is usually fatal in 3 to 4 days.
Hormone-responsive incontinence occurs in neutered dogs of both sexes and occasionally in spayed female cats but occurs most commonly in female dogs. The pet can urinate normally, but they leak urine while resting. Physical examination and blood and urine tests are usually normal in these pets. Hormone-responsive incontinence can occur months to years after a pet is neutered.
As pets age they may become incontinent. This may be due to a weakening of the muscles that hold urine in the bladder. There are many diseases that can cause a pet to create more urine than normal (polyuria) and several of these occur in older pets. If a pet has one of these diseases and often has a full bladder, the full bladder can push against the weakened sphincter and cause incontinence. Older pets can also develop senility and simply be unaware that they are dribbling urine.
Dogs and cats with brain or spinal cord disease may either dribble urine or be unable to pass urine. Most often they will have other signs of nervous system disease such as muscle weakness or paralysis.
A less common cause of incontinence in female dogs is called vulvovaginal stenosis. It is a condition in which the vagina at the level where the urethra ends is narrowed. Occasionally when the pet urinates, some urine will get trapped in the vagina in front of this narrowed area. Then when they rise after lying down the urine pours out. This condition can be diagnosed by feeling the vagina with a gloved finger. In some dogs the narrowing can be stretched under anesthesia. The incontinence may or may not resolve as sometimes other defects are also present.
Causes
Incontinence can also be confused with submissive urination. Submissive urination occurs when a dog is acting submissive to a person or to another dog. Submissive urination occurs more frequently in young animals. The dog usually rolls on its back and urinates. These dogs can also urinate normally.
Young animals may have a birth defect causing incontinence. The most common birth defect that causes incontinence in young dogs is ectopic ureter(s). The ureters carry urine from the kidneys to the bladder. If one or both ureters by-pass the bladder and connect to an abnormal location such as the urethra or vagina, the puppy may drip urine. Siberian Huskies are most often affected.
Other breeds that have a higher occurrence of this birth defect include:
Miniature Poodle
Labrador Retriever
Collie
Welsh Corgi
Wire-haired Fox Terrier
West Highland White Terrier
Female dogs are more commonly affected. If only one ureter is abnormal the dog will dribble urine but can also urinate normally. If both ureters are affected then the puppy will only dribble urine and cannot pass urine normally.
Treatment
Whenever possible treatment for urinary incontinence will be determined by the underlying cause. Definitive treatment involves elimination of the underlying cause of the urinary incontinence. Examples include correction of an anatomic defect, removal of a neurologic lesion, relief of partial obstruction, effective treatment of bacterial urinary tract infection.
In many cases, the cause of incontinence remains unknown after all diagnostic tests have been performed. In this instance, urinary incontinence must be treated symptomatically. The drug phenylpropanolamine is commonly used to treat urinary incontinence thought to be caused by weakness of urethral muscle (sphincter mechanism incompetence).
