Have you noticed your dog seems “off” – perhaps unusually tired, having stomach upset, not eating or even experiencing concerning episodes of weakness? While these signs can point to many things, they could also be red flags for a complex but manageable internal medicine condition called Addison’s disease. Often subtle in its early stages, Addison’s can sometimes reveal itself through a critical imbalance in the body’s electrolytes, particularly a concerning rise in potassium levels.
This blog will discuss canine Addison’s disease, shedding light on what it is, which breeds might be more likely to have it, its various causes, the tell-tale signs in blood work, the symptoms to watch for, and how this condition is acutely treated and managed long-term, offering a positive outlook for affected dogs.
What is Addison’s Disease?
Also known as hypoadrenocorticism, Addison’s disease is an endocrine (hormone) disorder that occurs when your dog’s adrenal glands, two small glands located near the kidneys, don’t produce enough of certain vital hormones. These hormones are primarily:
- Glucocorticoids (cortisol): These are instrumental in regulating metabolism, the stress response, immune system function, health of the digestive tract, and blood pressure.
- Mineralocorticoids (aldosterone): These play a critical role in maintaining the balance of electrolytes, especially sodium and potassium, and regulating fluid balance and blood pressure.
When the production of these hormones is insufficient, a cascade of problems can occur throughout the body.
There is a form of the disease referred to as “atypical Addison’s disease”. With this, dogs are only deficient in glucocorticoids and, for reasons poorly understood, are able to maintain their mineralocorticoids at healthy levels.
Addison’s disease wasn’t named arbitrarily or linked to any blood work abnormalities. In fact, it was named after Dr. Thomas Addison, a human physician who discovered the disease in 1855 and recognized the crucial role of the adrenal glands in the development of its symptoms.
Dog Breeds Suseptible to Addison’s
While Addison’s disease can affect any dog, certain breeds appear to have a higher predisposition, suggesting a genetic component. Some breeds more commonly diagnosed include:
Standard Poodle |
Bearded Collie |
Nova Scotia Duck Tolling Retriever |
Portuguese Water Dog |
West Highland White Terrier |
Great Dane |
Rottweilers |
Pomeranian |
Soft Coated Wheaten Terrier |
Labrador Retriever |
English Cocker Spaniel |
Great Pyrenees |
It’s important to remember that this is not an exhaustive list, and mixed-breed dogs can also develop Addison’s disease.
Other Causes of Addison’s Disease
The most common cause of Addison’s disease in dogs is immune-mediated destruction of the adrenal glands, where the body’s own immune system mistakenly attacks and damages the adrenal glands.
Less common causes include:
- Medications such as trilostane and mitotane can suppress adrenal function
- Trauma, surgery or infection affecting the adrenal glands
- Cancer that infiltrates the adrenal glands
It’s worth noting that in many cases, the exact cause remains unknown (idiopathic).
Symptoms of Addison’s Disease
The symptoms can be vague, waxing and waning, and can mimic many other conditions, earning it the nickname “the great imitator.” This is why it can be challenging to diagnose.
Common signs include:
- Lethargy and weakness
- Decreased appetite
- Vomiting, sometimes with diarrhea
- Weight loss
- Increased thirst and urination
- Shaking or trembling
- Slow heart rate (from hyperkalemia)
- Collapse (Addisonian crisis)
An Addisonian crisis is a sudden, severe, and life-threatening manifestation of the disease. It occurs when the body is unable to cope with stress due to the lack of hormones. Signs of a crisis include profound weakness, collapse, shock, severe vomiting and diarrhea, and can be fatal if not treated immediately.
Dogs with atypical Addison’s disease may primarily show gastrointestinal signs like chronic or intermittent vomiting, diarrhea, and poor appetite, without the electrolyte imbalances seen in typical Addison’s.
Blood Work Changes to Expect
Blood tests are crucial in diagnosing Addison’s disease. Several changes can raise suspicion, but one of the most characteristic findings, particularly in typical Addison’s disease (deficiency in both glucocorticoids and mineralocorticoids), is an elevated potassium level (hyperkalemia) and a decreased sodium level (hyponatremia). This imbalance is a result of the lack of aldosterone hormone.
Other potential blood work abnormalities include:
- Elevated kidney values (azotemia) specifically SDMA, BUN and creatinine
- Low blood sugar (hypoglycemia)
- Low red blood cell count (anemia)
- Lack of a “stress leukogram” on a complete blood count (CBC), which is the expected increase in certain white blood cells seen in stressed or ill animals with normal cortisol function
- The definitive test for Addison’s disease is the ACTH stimulation test
- In cases of so-called atypical Addison’s disease, the ACTH stimulation test will show the low cortisol but normal or near-normal sodium and potassium levels because mineralocorticoid production is preserved
Immediate, Life-Saving Treatment
An Addisonian crisis is a medical emergency requiring immediate hospitalization and rapid treatment. Several days of hospitalization for intensive care is typically needed to address all the abnormalities that an Addisonian crisis causes.
- Restore fluid balance: Intravenous fluids are given to correct dehydration and improve blood pressure.
- Correct electrolyte imbalances: Intravenous fluids and sometimes specific medications are used to lower the potassium and increase the sodium levels. Extremely high potassium levels can slow the heart, and in extreme cases, cause cardiac arrest.
- Administer glucocorticoids: Fast-acting injectable corticosteroids are given to replace the deficient cortisol and help the body cope with the stress of the crisis.
- Reverse hypoglycemia: If blood sugar is low, dextrose is added to the intravenous fluids.
Chronic, Lifelong Treatment
Once the patient is stable and released from the hospital with the diagnosis confirmed, long-term management begins. This is a lifelong commitment to supplementing the missing hormones.
For dogs with typical Addison’s disease (both glucocorticoid and mineralocorticoid deficiency), treatment involves:
- Mineralocorticoid replacement: Currently, this is typically done with a monthly injectable medication called desoxycorticosterone pivalate (DOCP, like Percorten-V® or Zycortal®). These medications help the kidneys retain sodium and excrete potassium. The dosage is adjusted based on regular monitoring of electrolyte levels.
- Glucocorticoid replacement: Low doses of oral glucocorticoids (prednisone) are also necessary. The dose may need to be increased during times of stress (e.g., surgery, illness, travel).
For dogs with atypical Addison’s disease (glucocorticoid deficiency only), long-term management primarily involves:
- Glucocorticoid replacement: Low doses of oral glucocorticoids (like prednisone) are administered. The monthly mineralocorticoid replacement is not needed as their body still produces sufficient aldosterone.
Dogs with atypical Addison’s should have their electrolytes monitored periodically, as some may eventually progress to the typical form of the disease and require mineralocorticoid supplementation.
Prognosis
The prognosis for dogs diagnosed with Addison’s disease and properly managed is generally excellent. With consistent medication and regular veterinary monitoring, most dogs with Addison’s can lead normal, happy lives.
It’s important for owners to be diligent in giving medications as prescribed and to work closely with their veterinarian to monitor their dog’s progress and adjust dosages as needed. While Addison’s requires lifelong care, it is a very manageable condition, and the majority of affected dogs can maintain a good quality of life.
Contact Us, We Speak Addison’s Disease
If you notice any of the symptoms mentioned above in your dog, especially if they are a breed known to be susceptible to Addison’s disease, don’t hesitate to contact us. Early diagnosis and treatment are key to managing Addison’s disease and ensuring your canine companion thrives and lives their best, happiest life!
Author:
James Woods DVM, MS, DACVIM (SAIM)
Ph: (912) 721-6410
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