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– Gorgeous George,
an Atypical
AD Dane –
December 1,
2003 – For the past two weeks we've been discussing Addison's
Disease (hypoadrenocorticism) in dogs. Canine Addison's
is a potentially fatal adrenal disorder that occurs in certain predisposed breeds
such as Great Danes. Other breeds affected are Portuguese Water Dogs, Standard
Poodles,
West Highland
White Terriers, Bearded Collies, Basset Hounds and Rottweilers. Addison's is
often misdiagnosed by veterinarians because symptoms frequently mimic those of
other
diseases. Fortunately
Addison's
Disease – if caught in time – is a condition that can
be effectively managed, enabling affected dogs to lead normal, happy lives.
Types of Addison's Disease
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Primary AD Symptoms:
Dogs with Primary Addison's often exhibit gastrointestinal problems,
such as loss of appetite, vomiting or diarrhea.
They can appear weak, easily fatigued, and depressed.
They may also exhibit a generalized weakness in their
hind quarters and/or they may limp.
Their fur can be affected
in a variety of ways, too. Some dogs
may develop a thicker coat, while others may lose fur. Some dogs might even
develop a curly coat – or lose the curl they've always had.
(Note: All these symptoms
can "wax and wane," further
confusing both owner and clinician.)
Addisonian
Crisis
If
left untreated, an affected dog could experience
an Addisonian Crisis:
The dog may collapse,
go into shock, have a slow or irregular heart rate, low blood pressure.
He may be dehydrated and show signs of what appears to be (but is
not) acute renal failure. If inappropriately treated, it is likely the
dog will die. |
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There are two basic types of AD: Primary
(Typical) Addison's and Atypical Addison's. We spent most of last
week talking about Primary Addison's Disease, which is by far the
easiest to diagnose and most common form of the disease.
Primary/Typical AD
In dogs, Primary
Addison's Disease is thought to be a consequence of immune dysfunction.
The body's immune
system
inappropriately
attacks
the dog's adrenal glands. The damaged adrenals are then unable
to produce adequate amounts of
two important types of hormones, mineralocorticoids and glucocorticoids,
which are essential to good health. See
last week.
Atypical AD
Atypical Addison's Disease also
results from adrenal failure (again, probably immune-mediated),
but Atypical AD involves underproduction of the glucocorticoids only. The dog's
mineralocorticoid levels remain
normal. Atypical AD is often just an early form of Primary
Addison's, meaning the adrenal glands are beginning to fail. They
may eventually lose the ability to produce mineralocorticoids as well, leading
the
patient right into Primary AD.
Detection of Atypical AD
Detection and diagnosis of Atypical Addison's can be even
trickier than Primary AD. This is because most affected dogs experience
intermittent
and varying or vague problems that seem to respond
to a simple course of antibiotics or Prednisone, only to resurface again later
on. Such symptoms may include (but are not limited to) lack of appetite, weakness,
vomiting, diarrhea, lethargy/depression, and joint pain.
Kelli Artinian's "Gorgeous George" (pictured
above) is a six-year-old Great Dane with Atypical AD. Kelli writes:
You can add George's story
to the others. He was diagnosed with the "Atypical" or Glucocorticoid
form of Addison's Disease during a routine blood test.
Our vet noted that his Eosinophil count (a type of white blood cell) was off
the charts. After she ruled out the most common causes (allergy and/or parasitic
infection) she gave George the ACTH Stimulation Test and his result was ZERO,
meaning George could not produce any hormones in response to stress.
His condition is well-managed now with
small doses of maintenance Prednisone. It is my job to determine when he
needs
more Pred to help him cope with a possible stressful situation, which is not
always easy to determine. I am happy to report that George has been living with
Atypical AD for several years now without any signs or
symptoms of the disease. I am grateful to my vet for being so persistent
in her effort to identify his problem.
Because George showed no obvious symptoms that
anything was wrong, he was lucky to get such an early diagnosis.
Congratulations to his inquisitive and well-schooled vet
for her great detective work!
Is Addison's Disease Inherited?
Unfortunately – as
you've seen – Addison's Disease is present in our beloved Great Dane
breed. Until more studies are done, we won't really know for sure how big a
role it plays and how it may be passed from generation to generation, but it
does appear to be an inherited disorder.
JP Yousha, chair of the
Great Dane Club of America's Health & Welfare
Committee tells us,
"In
dogs,
the
disease
is thought to be immune-mediated, meaning immune dysfunction
results in the atrophy of the adrenal glands. There is strong evidence for
familial tendencies in several breeds. Dr. Anita Oberbauer of the University
of California
(UC Davis)
has
studied the inheritance of the disorder in several breeds, and it appears that
two normal
carrier parents contribute to Addison's
Disease in the affected offspring."
She goes on to say,
"The GDCA
is seeking
Great
Dane families where at least one member has
been diagnosed
by
a veterinarian
with
Addison's for a
potential research project into the genetics and heritability of the disease
in this breed. A minimal population of 50 affected dogs (i.e. Danes with Addison's)
is necessary. A population of related dogs with known health status will be
required to complete the study, so each volunteer needs to be able to offer
some close relatives into the study. Ideally each Addison's Dane should be
able to
also provide the health status of approximately 5 close family members (i.e.
parents, siblings, offspring).
If you have or know of
some Danes who could help us explore this disease in our breed, please contact
me. All that is needed from the dogs will be a simple DNA sample the owner
can take with a cheek brush that will be supplied – that, and to fill out
some paperwork for the researcher. There is no further obligation, no blood
or
examinations are required, and anonymity is assured, as the dogs will be numbered
for the study. So the family relationship needs to be accurate, but pedigrees
and official names are not necessary."
If you have an affected Dane that might qualify
for this research project, please contact JP Yousha, GDCA Health and
Welfare Committee chair, at chromadane@juno.com or
(432) 684-8940. All inquiries will be strictly confidential.
I
urge you to support any and all research into Canine Addison's Disease.
Helpful Links
The following resources provide additional information about Canine Addison's
Disease:
All finished!
This ends our discussion on Canine Addison's Disease. It is a topic that I've
wanted to cover for a long time, but it took a big push from JP Yousha to get
the ball rolling. Addison's is a deadly disease
that is often missed by the average veterinarian because
it is uncommon in most breeds and the symptoms are deceiving. I
hope this series raises awareness and saves a few dogs.
Special thanks to JP
Yousha, Bobbie Palsa and Marc Sayer for
all their help, because this was not an easy subject. Thanks also to all
the people who contributed comments and stories about their experiences
with Canine Addison's Disease. I feel fortunate to be part of such an active
online community!
Archived comments (16) |
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