What is Cushing's Disease?
Cushing's Disease is a condition in which the adrenal glands
overproduce certain hormones. The medical term for this disease is
adrenal glands produce several vital substances, which regulate a
variety of body functions and are necessary to sustain life. The
most widely known of these substances is cortisol, commonly
known as cortisone. Decreased or excessive production of these
substances may be life-threatening.
does this disease occur?
There are three mechanisms by which this disease can occur.
Regardless of the cause, the clinical signs are essentially the
same. It is important to identify the type of Cushing’s Disease
because the various forms are treated differently and have different
Pituitary gland tumor.
The most common cause of Cushing's Disease (85% of all cases) is a
tumor of the pituitary gland. The tumor may be either benign or
malignant. The tumor causes the pituitary to overproduce a hormone
that stimulates the adrenal glands. Excessive cortisol secretion
then occurs. The tumor may be microscopic or quite large. Depending
on the size of the tumor, clinical signs other than Cushing's
Disease may be present. Generally, if the activity of the adrenal
gland can be controlled, many dogs with this form of Cushing's
Disease can live normal lives for many years as long as they take
their medication and stay under close medical supervision. Growth of
the pituitary tumor would give the patient a less favorable
Adrenal gland tumor.
Cushing's Disease may be the result of a benign
or malignant tumor of the adrenal gland. If benign, surgical removal
cures the disease. If malignant, surgery may help for a while, but
the prognosis is less favorable than for a benign tumor.
Iatrogenic Cushing's Disease means that the excess of
cortisol has resulted from excessive administration of a steroid.
This may occur from oral or injectable medications. Although the
injections or tablets were given for a legitimate medical reason,
their excess is now detrimental.
What are the clinical signs?
most common clinical signs associated with Cushing's Disease are an
increase in appetite, water consumption, and urination. Lethargy, or
lack of activity, and a poor hair coat are also common. Many of
these dogs develop a bloated appearance to their abdomen due to an
increase of fat within the abdominal organs and a stretching of the
abdominal wall as the organs get heavier. The pot-bellied appearance
also develops because the muscles of the abdominal wall become
weaker. Panting is another common finding with this disease.
is it diagnosed?
number of tests are necessary to diagnose and confirm Cushing's
Disease. The two most common tests to detect Cushing’s Disease are
the ACTH Stimulation Test and the Low-Dose Dexamethasone Suppression
Test. Other tests are needed to decide which form of the disease is
present. An ultrasound examination can be a valuable part of the
testing process. This permits visualization of the adrenal glands
and determines their size and the presence of a tumor. Although some
of these tests are somewhat expensive, they are necessary.
are the treatment options?
Cushing's Disease: Treatment of this form
requires a discontinuation of the steroid that is being given. This
must be done in a very controlled manner so that other complications
do not occur. Unfortunately, it usually results in a recurrence of
the disease that was being treated by the steroid. Because there may
have been adverse effects on the adrenal glands, treatment is also
needed to correct that problem.
Tumor. Treatment of an adrenal tumor
requires major surgery. Although this is a high risk surgery, if
successful and the tumor is not malignant, there is a good chance
that the dog will regain normal health. If surgery is not an option,
some of these patients can be managed with the medication discussed
Pituitary Tumor: Treatment of the
pituitary-induced form of Cushing's Disease is the most complicated.
There are two drugs commonly used: Anipryl and Lysodrenä.
Anipryl is the only drug approved by the FDA to treat canine
Cushing’s Disease. Anipryl is given daily and has little, if any,
side effects. Few blood tests are required when using this
medication. Anipryl works directly on the pituitary gland, helping
produce more of the hormones that may be diminished with Cushing’s
Disease. Most pets with uncomplicated Cushing’s Disease (no
complications such as diabetes mellitus, etc.) can be treated with
Anipryl and most clinical signs will resolve. If a pet does not
improve after two to three months of Anipryl therapy, Lysodrenä
therapy is often recommended.
is the primary drug used to destroy the abnormal adrenal gland
is also known as mitotane or o,p'-DDD. If not enough drug is used,
the abnormal tissue persists and the disease continues. If too much
is used, most or all of the adrenal cortex will be destroyed, which
can be life-threatening. Therefore, careful monitoring of the dog is
necessary in order to achieve good results. Because the pituitary is
not being affected by the treatment, it continues to stimulate the
adrenal gland. This means that continued treatment is necessary.
Although a cure is not achieved with either treatment, control is
possible for many years if the tumor is small. If the tumor is
large, local effects of the tumor invading surrounding tissues in
the brain can be the limiting factor in survival.
INSTRUCTIONS FOR LYSODREN TREATMENT OF CUSHING’S
Treatment of this
form involves an initiating phase and a maintenance phase.
The initiating phase arrests the disease and restores the dog
to a more normal state. Some of the clinical signs, especially
increased food and water intake, should stop within the first 1-3
weeks. Other signs, such as a poor hair coat or a bloated abdomen,
may take several weeks or months to correct. The maintenance
phase represents the phase of long-term therapy. This phase
lasts the rest of the dog's life.
continually monitor your dog's food and water intake. We expect both
to return to a normal level. Water intake should be less than 1 oz
per pound (66 cc per kilogram) of body weight per day, but don't
limit the water if your dog needs to drink more. Your dog should
drink _________________ ounces (__________cc) per day. The amount of
food should also be measured each day. At least two feedings per day
Give ________ Lysodrenä
tablet(s) one time per day beginning on _______________ for 9 days
or until one of the following occurs:
a) Your dog's water intake drops to the 1 oz per
pound (66 cc per kilogram) per day level or ___________ per day.
dog's appetite returns to normal or it takes 15-30 minutes to eat
when it would normally eat in much less time.
c) Your dog does not eat a regular meal.
d) Your dog vomits.
e) Your dog has diarrhea.
e) Your dog becomes unusually listless.
Return in nine days or when one of the above occurs
for another ACTH stimulation test. This test should be done early in
the morning and will require your dog to be in the hospital for
about 4-5 hours. If the test is abnormal, the initiating phase will
continue. If the test is normal, the maintenance phase will begin.
If loss of appetite, vomiting, diarrhea, or
listlessness occurs, give________ tablet(s) (_______ mg) of
hydrocortisone twice daily for two days. DISCONTINUE THE LYSODRENä
TABLETS. If vomiting prevents oral administration, your dog must be
seen by a veterinarian for administration of proper medication by
injection. When you begin this treatment, please call us for
consultation and instructions.
Following the first
two days of treatment with ________ tablet(s) twice daily, give
________ tablet(s) twice daily for two more days, then ________
tablet(s) twice daily for three days, then ________ tablet(s) once
every other day for one week. At the end of that time, make an
appointment so we can assess the situation and give you further
instructions on Lysodren administration.
Report any other changes in your dog's behavior that
are out of the ordinary. This disease and this treatment can result
in several abnormal behaviors. However, your dog can also have other
diseases that occur concurrently but independently of Cushing's
Disease. It is important that we differentiate between the two
situations so that proper treatment can be taken.
Stay cautiously optimistic. This is a serious
disease, but many dogs with Cushing's Disease enjoy a greatly
improved quality of life for many years.
regulated, your dog will take Lysodrenä
approximately once weekly. An ACTH stimulation test will be
necessary about every 3-4 months to be sure that regulation is
satisfactory. At the appropriate time, the specifics of the
maintenance phase will be explained.
Give _________ tablet(s) every ________ days.