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Canine Addison's Disease
Roger Ross
DVM
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Addison's disease is a condition
that occurs when the adrenal glands stop producing hormones.
We vets often miss this disease because the symptoms are vague...just not
feeling well, off and on digestive and intestinal problems, weakness, and
so forth. Poor body condition, dehydration, a weak pulse, a slow heart rate,
and blood in the stools are other common signs, but that's true of a lot of
diseases. And the signs often come and go over a long period of time.
One of the big hints that your pet may have Addison's is that it gets sick
fairly often, but everytime the vet gives it fluids and/or steroids, it gets
better for a while.
Often, it's not until the patient is critically ill that diagnose the disease.
This is yet another example of why performing routine blood work on sick animals
is beneficial: we can diagnose these types of problems before they become
an emergency.
Blood work may indicate: anemia, electrolyte imbalances (elevated potassium,
low sodium, and low chloride), low blood sugar, elevated calcium, acidosis,
and elevation of liver and kidney values
Any age dog can get this disease, but it tends to be seen in middle aged
female dogs. Especially female dogs that haven't been spayed. About one third
of cases are mixed-breed dogs, but there appears to be some breed predilection
toward Poodles, Portuguese water dogs, Great Danes, Sheperds, and Rottweilers.
There is no "cure", but with treatment, (lifelong) most pets live a pretty
normal life. The drugs most commonly used to treat Addison's disease are some
combination of prednisone, Florinef, and DOCP. We need to monitor your dog's
blood on a regular basis so we can adjust the doses of these medications as
needed. All three of these medications frequently cause mildly troublesome
side effects, so we often have to deal with those. We refer to this process
as "careful management" .
Approximately 35% of dogs with this disease present in what is known as
Addisonian crisis; this is a true emergency and immediate treatment is required
to save the dog's life. These animals have the classic signs of shock: mental
dullness, pale mucous membranes, weak pulses, and cold extremities. In addition,
they have an abnormally slow heart rate due to elevated blood potassium levels.
A Little About The Disease:
Mammals, in general, have 2 adrenal glands. Their job is to produce the
steroidal hormones that help regulate cellular function. In Addison's disease,
the part of the adrenal glands that produce cortical steroids is diseased
and not functioning well.
There may be no clinical signs of disease until 90% of the adrenal cortex
has ceased to function. The usual cause of the destruction of the adrenal
glands is thought to be auto-immune...for reasons we don't understand well,
the body's immune system attacks it own cells. This occurs in other organs
as well. In fact, many of our diseases are auto-immune type problems.
One of the more interesting causes of Addison's Disease is from steroid
therapy. Usually it's associated with long term steroid treatment for something
like severe skin allergies, and then for some reason or other, the steroid
treatment is stopped. Another medication called Lysodren can cause Addison's
disease as a side effect.
DIAGNOSIS
Once we suspect your pet has Addison's Disease, there is no simple, cheap,
in-clinic test to prove it, which is a nuisance, but there is a fairly straight
forward test called an ACTH Stimulation test that is definitive. ACTH will
stimulate a normal adrenal gland to produce alot of cortisol. If very little
cortisol is produced, then we know for certain that your pet has Addison's
Adrenal Gland Disease. Once a certain diagnosis is made, then life long treatment
will be needed if you want to keep your pet.
TREATMENT
Inital treatment of a dog in suspected "Crisis" is lots of IV Fluids and
high dose steroid injections. Your vet will do everything he or she can to
get the body temperature up to normal and treat the other secondary problems
associated with a patient in shock.
At the same time, expect a lot of testing to be done to confirm the suspected
diagnosis and to look for other problems. These dogs that are in Addisonian
Crisis are rapidly dying and we need to rule out heart failure, toxic shock,
poisoning and other causes of weak, cold, slow heart rated emergency patients.
Once the patient is stablized, treatment involves replacing synthetically
the hormones a healthy adrenal gland would produce. Since the adrenal gland
produces two major types of steroid hormones (cortical or gluco-corticoid
and mineral-corticoid) we usually treat this disease successfully by giving
prednisone (inexpensive and readily available) and either fludrocortisone
(Florinef) orally or a once a month injection of DOCP (Percorten-V) These
last two meds are a little expensive and your vet may not keep them on hand.
It's not quite as easy as I make it sound, like diabetes, it takes repeat
testing, trial and error, and frequent adjustments in the medication to get
everything just right so that your dog can lead a long and comfortable life.
reprinted with kind permission from Roger Ross DVM
The above information is simply informational. It's intent is not
to replace the advice of a veterinarian nor to assist you in making a diagnosis
of your pet. Please consult with your own veterinarian for confirmation of
any diagnosis. Your pets life may depend on it.