Problem starts when adrenal glands stop making cortisol and aldosterone, says Yung-Tsun Lo (D.V.M, Ph.D) of Bioguard Corporation.
Addison’s disease — also called hypoadrenocorticism — is basically when a dog’s adrenal glands stop making enough of two really important hormones: cortisol and aldosterone. Cortisol is the “stress hormone,” it helps the body handle everyday challenges.
Aldosterone keeps sodium and potassium balanced, which is critical for hydration, blood pressure, and even heart rhythm.
How does It Affect the Body?
So, when we talk about Addison’s disease, there are two main hormone problems going on.
First, cortisol deficiency. Cortisol is the hormone that helps the body cope with stress, keeps metabolism running smoothly, and regulates the immune system. Without enough cortisol, dogs can’t handle stress well, their energy balance gets thrown off, and their immune system doesn’t function properly.
Second, aldosterone deficiency. Aldosterone is all about balancing sodium and potassium. If it’s missing, sodium levels drop and potassium builds up. That leads to dehydration, low blood pressure, and even abnormal heart rhythms.
And what’s the cause? In most cases, it’s the dog’s own immune system attacking and destroying the adrenal glands. Less commonly, it can be due to tumours, infections, or even stopping long-term steroid medications too quickly.
What are the Signs of Addison’s Disease?
When Addison’s disease starts, the signs are often subtle and vague. Dogs might seem a little off — tired, not eating well, maybe some vomiting or diarrhea, and gradual weight loss. These are easy to miss because they look like so many other minor issues.
As the disease progresses, things get more serious. You’ll see weakness, collapse, dehydration, and even a drop in body temperature. At this stage, it’s clear something major is wrong.
The most dangerous situation is an Addisonian crisis. That’s when the dog goes into acute shock.Sodium levels plummet, potassium shoots upand the heart slows down (bradycardia). Withoutimmediate emergency care, this stage can be fatal.
How is Addison’s Disease Diagnosed?
When Addison’s disease is suspected, the first signs often appear in bloodwork. Typical findings include low sodium and high potassium, which are strong indicators. Kidney values may also be elevated, sometimes mimicking kidney disease at first glance.
To confirm the diagnosis, the ACTH stimulation test is used — the gold standard. In this test, a dose of ACTH (the hormone that normally stimulates the adrenal glands) is administered, and cortisol levels are measured. In dogs with Addison’s disease, cortisol fails to rise.
An ECG can provide additional information, as high potassium levels may slow the heart rate, leading to bradycardia.
In summary: Bloodwork offers the initial clues, the ACTH test provides definitive confirmation and the ECG helps assess the severity of electrolyte imbalances.
How is Addison’s Disease Treated?
When a dog suffers from an Addisonian crisis, the immediate priority is emergency care. Treatment involves administering IV fluids to stabilize circulation, glucocorticoids to replace the missing cortisol, and correcting the dangerous electrolyte imbalances. This intervention is truly life-saving.
After the crisis is resolved, attention shifts to long-term management. Dogs with Addison’s require lifelong hormone replacement therapy:
Glucocorticoids (such as prednisone) to restore cortisol levels
Mineralocorticoids (DOCP injections or oral fludrocortisone) to replace aldosterone. Because each dog responds differently, regular blood tests are essential to adjust medication and maintain proper sodium and potassium balance.
The encouraging news is that with consistent treatment and monitoring, the prognosis is excellent. Most dogs go on to live full, healthy, and happy lives — often indistinguishable
from dogs without Addison’s disease.
Conclusion
Addison’s disease in dogs is rare but serious. We often call it “the great pretender” because the symptoms look like so many other illnesses, which makes it tricky to spot.
The most important thing is catching it early — recognizing those vague signs before they turn into a full-blown crisis.
And the good news? With the right treatment and regular monitoring, dogs with Addison’s can go on to live happy, healthy, normal lives.
















