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Pre-Surgical Information
Spaying or neutering your pet is a big step! There is a lot to consider
when we are planning your pet’s surgery. Here is some information to help
you make wise decisions.
Click here . . .
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Special LibraryOur Special Library
is a collection of informative articles on a variety of health topics.
Click here . . .
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Discharge InstructionsClick here for
information on how to care for your pet at home.
Click here . . .
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Cushings Disease
Cushing's Disease is a uncommon condition
in older dogs, often mistaken for the aging
process itself. Yet Cushing's disease is treatable,
and that treatment can result in a longer, more
comfortable life for the dog and its owner.
Cushing's Disease is one of the less common endocrine
diseases of dogs. An endocrine disease is a disease
affecting one of the many glands that make hormones.
Hormones are chemicals that the body makes to regulate itself.
A more common example of an endocrine disease would be diabetes.
The pancreas makes insulin, which is a hormone that causes the
cells to absorb glucose. After meals, when the blood sugar
levels rise, the pancreas releases insulin, which travels to all
parts of the body and causes all the cells to absorb the glucose
that is in the blood. When the pancreas goes bad, not
enough insulin is produced, and we have an abnormal condition
known as an endocrine disease.
In the case of Cushing's Disease, the hormone in question is cortisol. Cortisol is also known as adrenalin, and is
a hormone made by the adrenal glands. The adrenal glands
sit just next to the kidneys, and in response to stress they
produce cortisol. Cortisol travels to all parts of the
body, where it has many effects. In patients with Cushings
disease, too much cortisol is produced. This abnormal
condition is also called hyperadrenocorticism (hyper for hyper,
adreno for adrenal, corticism for cortisone).
Cushing's Disease has many symptoms. Cortisol has many
target tissues, and it affects each target tissue in a different
way. Thus, we see many different symptoms in Cushingh's
Disease.
The most common symptoms include:
• increased/excessive water consumption (polydipsia)
• increased/excessive urination
(polyuria)
• urinary accidents in previously
housetrained dogs
• increased/excessive appetite
(polyphagia)
• food stealing/guarding,
begging, trash dumping, etc.
• sagging, bloated, pot-bellied
appearance
• weight gain or its appearance,
due to fat redistribution
• loss of muscle mass, giving the
appearance of weight loss
• bony, skull-like appearance of
head
• exercise intolerance, lethargy,
general or hind-leg weakness
• new reluctance to jump on
furniture or people
• excess panting, seeking cool
surfaces to rest on
• symmetrically thinning hair or
baldness (alopecia) on torso
• other coat changes like
dullness, dryness
• slow regrowth of hair after
clipping
• thin, wrinkled, fragile, and/or
darkly pigmented skin
• easily damaged/bruised skin
that heals slowly
• hard, calcified lumps in the
skin (calcinosis cutis)
• susceptibility to infections
(especially skin and urinary)
• diabetes, pancreatitis,
seizures
There are also some other signs of Cushing's Disease that are
only evident on blood tests. We see elevations in liver
enzymes (ALP, ALT, and AST), decreased thyroid levels, a
stress leukogram, and high blood pressure. There are
so many different sypmtoms of Cushing's Disease that it is
actually very uncommon for any one patient with Cushing's
Disease to show all the symptoms at the same time.
It can be quite difficult to diagnose Cushing's Disease.
There are four different tests that can be used to test for Cushings' Disease: the ACTH stimulation test, the Low-Dose
Dexamethazone Suppression test, the High-Does Dexamethazone
Suppression test, and the Urine Creatinine:Cortisol Ratio test.
Which one to use is a very complex decision, and involves both
the art and the science of veterinary medicine. It may
take two different tests to become relatively sure our patient
has Cushing's Disease. Like many things in life, there are
no sure things, and we may never be 100% sure that a patient has
or doesn't have Cushing's Disease. We use our best
judgement combined with common sense and a healthy dose of
caution and treat the way we feel is best for the patient.
Cushing's Disease is generally treated with a drug called
Lysodren. Although it is the best drug for treating this
disease, Lysodren is not a nice drug. It is fairly
expensive, and has the added benefit of being somewhat toxic.
Lysodren selectively targets the adrenal glands, which is just
the ticket if they are making too much cortisol. The goal
is to remove just enough adrenal tissue to restore the cortisol
levels to normal. The trick is getting the just enough
part right. Every individual is different, and each
requires a different dose. Lysodren is given at a high,
daily dose until enough adrenal tissue is gone to allow the
cortisol levels to return to normal. This is called the
induction phase, and it can take anywhere from three days to
three weeks. Lysodren is given at a dose of 25mg per
kilogram bodyweight every twelve hours immediately after a meal.
It is best to start Lysodren therapy on a Saturday to minimize
the chances of having problems on a weekend.
It takes careful observation to tell when a patient has reached
the end of the induction phase. Generally, we start dosing Lysodren at 25mg per kilogram of body weight every 12 hours.
Then we monitor very closely for signs that induction is over.
Dogs that get treated for Cushing's Disease are drinking a lot
of water, and they have a voracious appetite. When the
water consumption OR the appetite decrease, we have reached the
end of the induction phase. We are not talking about major
changes, either. A slight decrease in appetite, say where
the dog still eats well but does not wolf the food down like
he did before is enough. If you have any questions at all
about whether your dog has reached the end of the induction
phase, please call immediately and discuss your observations
with the veterinarian. If your dog has not responded to Lysodren therapy by eight of ten days, we will need to examine
him or her, and we may perform the ACTH stimulation test at that
point if there are any questions as to what is going on.
There are serious consequences for over-shooting the induction
phase end-point. If we over-shoot the end-point, we will see
signs of toxicity. Sings of toxicity include lethargy,
staggering or incoordination, weakness, loss of appetite,
vomiting, and/or diarrhea. If you see any of these
symptoms, call the veterinarian immediately. We often send
home a small supply of a drug called prednisone. This is a
rescue drug that can be given if we have signs of toxicity.
Give the prednisone only if the veterinarian directs you to give
it.
When we think we have reached the end of the induction phase, we
do an ACTH stimulation test to find out for sure. If the
test shows good control, we will enter the maintenence phase.
In the maintenance phase, Lysodren is given at a dose of
either 25mg or 50mg per kilogram bodyweight once a week,
depending on how soon your dog responded to the induction phase.
It is still a good idea to give it just after a meal. If
signs of toxicity develop, lethargy, staggering or
incoordination, weakness, loss of appetite, vomiting, and/or
diarrhea, contact the veterinarian immediately. Similarly,
be sure and notify the veterinarian if signs of increased water
consumption or increased appetite develop.
The prognosis for dogs with Cushing's Disease is good with
treatment. We expect symptoms of Cushing's to fully
resolve over the course of 4-6 months. Excess drinking and
urinating abate quickly. It may take several months for hair and
coat improvement to be observed. Dogs generally are more
comfortable after the disease is under control and may live
happily for years. However, Cushing's disease is managed, not
cured, and maintaining a dog with Cushing's disease requires
vigilance and commitment on the part of the owner.
Left untreated, Cushing's disease will progress. As excess cortisol is immunosuppressive, Cushingoid dogs are prone to
various infections. They are also predisposed to developing
hypothyroidism, pancreatitis, diabetes, seizures, hypertension,
congestive heart failure, blood clots, and liver and kidney
failure. It should not go without noting that many of these dogs
are at risk of early euthanasia due to incontinence resulting
from increased water consumption. Although the treatment
for Cushing's Disease is not without it's own problems, the
treatment is much better than the disease, and treatment will
prolong the patient's life and improve the quality of life as
well.
Lysodren is not an inexpensive drug. The last time I
checked, it cost somewhere around $5.25 per pill. For a
twenty-pound dog who would get one-half tablet every twelve
hours during the induction phase, assuming induction took eight
days, it would cost about $45. Maintenence for that same
dog would be either $10.50 or $21.00 a month, dpending on the
maintenence dose.
It is important to monitor dogs on Lysodren periodically.
Generally, we need to repeat the ACTH stimulation test every 6
to 12 months. If signs of problems develop, we will also
need to repeat the ACTH stimulation test. All older dogs,
especially those with Cushing's Disease, need to have annual bloodwork done.
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