Urinary Incontinence and Bladder Problems in Dogs
Incontinence is loss of voluntary control over the act of voiding. This medical condition must to be differentiated from a housetraining problem and/or submissive urination, especially in young dogs. Incontinent dogs wet their bed or the floor where they are sleeping, urinate inappropriately in the house, sometimes dribble urine, and may void more frequently than normal. There may be an ammonialike odor about the dog's bedding. The skin around the penis or vulva may be scalded.
There are several types of urinary incontinence.
This common incontinence is seen most often in middle-aged and older spayed females, and less commonly in young females and older neutered males. It is caused by a deficiency of estrogen in females and testosterone in males. Both these hormones are important in maintaining muscle tone of the urethral sphincter.
Hormone-responsive incontinence is much like bedwetting. The dog urinates normally, but wets when relaxed or asleep.
Treatment: Hormone-responsive incontinence in spayed females is treated by giving phenylpropanolamine, a drug that increases the tone of the urethral sphincter. Diethylstilbestrol (estrogen) can be given if phenylpropanolamine is not successful. However, diethylstilbestrol is no longer the first choice for treatment because of the risk of bone marrow suppression. Phenylpropanolamine is periodically taken off the market, because it is also used in human diet supplements and can be abused. If it unavailable, your veterinarian will work with you to use the lowest dose possible of estrogen to control your dog's incontinence.
Incontinence in neutered males responds well to giving the dog testosterone. Phenylpropanolamine has also been used successfully in males.
This is another common problem, characterized by the release of urine caused by contraction of the abdominal wall muscles along with relaxation of the muscles that support the urethra-the normal voiding process. The dog passes small amounts of urine when she is upset or in a stressful situation. It has also been called stress incontinence. This is most common in young puppies in their new homes, and many will simply outgrow it.
Treatment: Submissive urination can be treated with phenylpropanolamine and/or other drugs that increase urethral tone while behavior modification techniques are applied. Keep stress-provoking interactions low key and brief, and avoid bending over the dog or making direct eye contact with her. Do not punish the dog, as this makes the incontinence worse. Working with a dog trainer or canine behaviorist is recommended to address this behavioral issue.
Spinal cord injuries, infections, tumors, and inherited neuropathies can interfere with the nerves that control the bladder. A bladder with a compromised nerve supply lacks muscle tone and cannot contract. The bladder continues to fill until the pressure exceeds the resistance of the sphincter mechanism that closes the urethra. This results in intermittent, uncontrolled dribbling.
Neurogenic incontinence can be confirmed with a cystometrogram. This is a test that measures how forcefully the bladder contracts in response to the introduction of incremental volumes of fluid into it through a catheter. The results also suggest the site of the neurologic deficit (the spinal cord or the bladder).
Treatment: Neurogenic incontinence is treated with long-term catheterization and antibiotics to treat and suppress infection. Drugs that act on the bladder may be of help. This type of incontinence is difficult to treat. The problem may totally resolve, however, in dogs whose spinal cord injuries have been successfully treated.
Incontinence from Overdistension of the Bladder
This type of incontinence is due to a partially obstructed bladder, caused by urethral stones, tumor, or stricture. The signs and symptoms are similar to those of neurogenic incontinence, but the nerve supply to the bladder is undamaged.
Treatment: Dribbling associated with an overdistended bladder is treated by correcting the cause of the obstruction and placing an indwelling catheter until the bladder regains its muscular tone. Drug therapy is also beneficial. Since the bladder is neurologically normal, treatment may eliminate the problem entirely.
This article is excerpted from “Dog Owner’s Home Veterinary Handbook” with permission from Wiley Publishing, Inc.
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