Dog Owner's Home Veterinary Handbook.pdf - Mr. Walnuts

Hormone-Responsive Incontinence
THE URINARY SYSTEM • 417
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.
Submissive Urination
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.
Neurogenic Incontinence
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).