Addison’s Disease in Dogs: Symptoms, Causes, and Treatment

How well does your dog handle stress?

For most dogs, stress is managed easily, thanks to the production of corticosteroid hormones. But when a dog develops Addison’s Disease, those hormones drop to dangerous levels, which can wreak havoc on the entire body.

Today we're talking about Addison's Disease in dogs - a mysterious and complex condition that can have serious consequences for our four-legged companions. In this blog post, we'll explore the key aspects of Addison's Disease, its causes, and how it can be managed. We'll also discuss how stress can play a role in your pup's illness and what warning signs to look out for. Let’s get started! 

What is Addison’s Disease in Dogs?

Addison’s Disease (also known as hypoadrenocorticism) is a condition in which an affected dog’s adrenal glands produce insufficient amounts of corticosteroid hormones. Though this condition is relatively uncommon (occurring naturally in less than 0.5% of dogs, according to the >Canadian Veterinary Journal>), those that are diagnosed with Addison’s should be cared for with the utmost diligence. 

Fortunately, this condition can typically be managed with medication - but to fully understand what Addison’s Disease is and how to treat it, we must first take a closer look at the role of the adrenal glands. 

Role of the Adrenal Glands in Regulating Stress

The adrenal glands are two small glands that live next to your dog’s kidneys. These glands are responsible for a few different things, though the most important is the production and regulation of the body's corticosteroid hormones - often referred to as the “stress” hormones. 

There are two unique classes of corticosteroids produced by the adrenal glands:

Glucocorticoids - This class plays a role in regulating blood pressure, inflammation, and metabolism, among other functions, while also influencing the metabolism of fat, sugar, and protein. Cortisol is perhaps the most recognized hormone in this class.

Mineralocorticoids - This class helps to maintain electrolyte and water balance in the body, as well as influences blood pressure. Examples of mineralocorticoids include aldosterone, which helps regulate sodium and potassium levels.

These hormones play an important role in the body’s reaction to physical and emotional stress, as well as regulating many physiological functions. So when the adrenal glands fail to produce them sufficiently, it can be quite problematic - this is what happens with Addison’s Disease. 

Risk Factors for Addison’s Disease in Dogs

Addison's Disease can affect any dog, regardless of age, sex, or breed, though it is most commonly seen in younger dogs between the ages of three and six. Female dogs may also be more likely to develop this condition than males. The most common breeds associated with Addison's Disease include:

• West Highland Terriers
• Great Danes
• Basset Hounds
• Portuguese Water Dogs
• Airedale Terriers
• Standard Poodles
• Bearded Collies

Symptoms of Addison’s Disease in Dogs

Addison’s Disease can be difficult to diagnose because many of its symptoms coincide with numerous other conditions. It is, for this reason, that this condition has been nicknamed “the great pretender.”

Symptoms of Addison’s Disease may wax and wane over time, and they are often very vague and non-specific, but they may potentially include: 

• Lethargy
• Loss of Appetite
• Vomiting
• Diarrhea 
• Weight Loss
• Increased Thirst and Urination 

Oftentimes, Addison’s Disease is discovered as an incidental finding during routine blood work, though your veterinarian may become suspicious if your dog has intermittent episodes of the aforementioned symptoms. Additionally, nearly 30% of dogs will be diagnosed following an Addisonian Crisis. 

What is an Addisonian Crisis?

An Addisonian Crisis is an acute event caused by the body’s inability to adapt to external or internal stressors. It is characterized by a sudden drop in blood pressure, severely elevated potassium levels, abnormal heart rhythms, a very slow heart rate, and severe hypoglycemia (dangerously low blood sugar). This potentially fatal crisis occurs when around 90% of the adrenal cortex - the outer layer of the adrenal gland - is not working properly.

An Addisonian Crisis is a true medical emergency that requires swift intervention to treat. In many cases, this will involve hospitalization with IV fluids and hormone replacement therapy. If left untreated, an Addisonian Crisis can quickly become fatal. 

What Causes Addison’s Disease in Dogs?

According to Dr. John August, a veterinarian in the College of Veterinary Medicine & Biomedical Sciences at Texas A&M University, there are two primary types of Addison’s Disease in dogs, each with its own distinct cause. 

Primary Hypoadrenocorticism is “an immune-mediated disease, which means that the body’s own immune system attacks the adrenal gland tissue,” while Secondary Hypoadrenocorticism occurs when “the adrenal tissue cells stop functioning spontaneously and die off.”

Primary Hypoadrenocorticism is typically hereditary, though it can also be drug-induced in rare cases with medications such as ketoconazole, trilostane, and lysodren. Secondary Hypoadrenocorticism, on the other hand, can occur as a result of brain trauma, cancer, inflammation, or congenital abnormalities.

There is also a third class of Addison’s Disease referred to as “atypical hypoadrenocorticism.” This occurs when only the cortisol hormone is affected, but not aldosterone. As a result, the dog's sodium and potassium electrolytes remain unaffected. This condition accounts for approximately 30-45% of all Addisonian cases, according to Dr. Doug Brum of MSPCA-Angell. 

In either case, it is imperative to keep a close eye on your pup’s progress. Routine bloodwork, regular wellness exams, and consistent medical management are key to keeping this condition well controlled. 

Diagnosing Addison’s Disease in Dogs

Veterinarians may use a combination of physical examinations, blood tests, imaging tests, and other diagnostic tools to diagnose Addison's Disease in animals.

Physical examination is usually the first step in diagnosing Addison's Disease. During this exam, the veterinarian will look for signs of dehydration or electrolyte imbalances, such as low blood pressure or an increased heart rate. The veterinarian may also check for skin changes, such as darkening around the eyes or mouth, which can indicate an underlying problem with the adrenal glands.

Blood tests are another common tool used to diagnose Addison's Disease in animals. These tests measure levels of hormones produced by the adrenal glands, including cortisol and aldosterone. Low levels of these hormones can indicate an issue with the adrenal glands and point toward a diagnosis of Addison's Disease. The most commonly used blood test in this instance is the ACTH Stimulation Test, which can also be used to diagnose Cushing’s Disease.

Imaging tests such as CT scans and MRIs are less common but can also be used to diagnose Addison's Disease in animals. These tests can help visualize the adrenal glands themselves, allowing your veterinarian to determine if there are any structural issues that could be interfering with hormone production.

Finally, veterinarians may use additional diagnostic tools, such as urine analysis or tissue biopsies, to confirm a diagnosis of Addison's Disease. Urine tests can measure hormone levels in the urine, while biopsies allow veterinarians to examine tissue samples from the adrenal glands directly under a microscope.

Addison’s Disease in Dogs Treatment

Treatment for Addison's Disease in dogs typically involves routine hormone replacement therapy to substitute the hormones that are not being naturally produced by the adrenal glands. 

Glucocorticoids (such as cortisol) are typically supplemented with daily oral steroids such as Prednisone, while Mineralocorticoids (such as aldosterone) are supplemented with an injection such as Percorten or Zycortal, which can be administered once per month. Alternatively, an oral medication called Florinef may also be used to replace both cortisol and aldosterone.

Working with your veterinarian, you can determine the best form of supplementation for your dog and lifestyle. It's important to monitor their clinical signs, electrolytes, and response to medication closely so that the amount of medication given can be reduced to the lowest effective dose and frequency over time.

Dogs experiencing an Addisonian Crisis are typically treated with intravenous fluid therapy to replenish electrolytes, steroids, and medications to manage abnormal heart rhythms, as well as to protect the GI tract. This treatment is highly effective, leading to a good chance of recovery, and dogs tend to respond quickly with the proper care.

Recovery and Long-Term Management of Addison’s Disease in Dogs

It is important to note that while hormone replacement therapy can help manage Addison's Disease in dogs, it does not cure it. Regular monitoring of blood levels and regular check-ups with your veterinarian are necessary to ensure your dog remains healthy and symptom-free.

Frequent blood work monitoring may be required at the onset of treatment and over the first three to six months while your veterinarian works to establish the most effective medication dosing intervals. Thankfully, with the appropriate care, most dogs with Addison's Disease can live a long and happy life.

FAQs About Addison’s Disease in Dogs

"Does Addison's disease in dogs come on suddenly?"

While the disease can come on suddenly, it is more common for the symptoms to develop gradually over time.

“Can Addison’s Disease in dogs go away?”

Unfortunately, according to Dr. John August from the College of Veterinary Medicine & Biomedical Sciences at Texas A&M University, “hypoadrenocorticism in pets cannot be prevented or cured.” 

“How common is Addison’s Disease in Dogs?”

According to the Canadian Veterinary Journal, Addison’s Disease occurs naturally in less than 0.5% of dogs. 

“How long can dogs live with Addison’s Disease?”

If diagnosed and treated with the correct medications, a dog can lead a normal, healthy life even with an Addison's diagnosis. However, if an Addisonian Crisis occurs and goes untreated, it can be fatal.

"Is Addison's disease in dogs hereditary?"

Yes, according to Dr. Aly Cohen of the Cornell Richard P. Riney Canine Health Center, “The most common cause of Addison’s disease is hereditary, and it causes the dog’s immune system to destroy their adrenal glands.” 

“Do dogs with Addison’s Disease need a specific diet?”

For dogs with Addison's disease, lifestyle modifications can be hugely beneficial in helping manage the condition. Adopting a low-sodium diet can help reduce the severity of symptoms while ensuring that your pet gets plenty of exercise can improve overall health. 

Owners should also monitor their pet's weight to avoid exacerbating the condition. Finally, be sure to keep regular appointments with your veterinarian so that any changes in the condition or symptoms can be monitored and treated accordingly.

“How are dogs tested for Addison’s Disease?”

ACTH stimulation testing is the most reliable way to diagnose Addison's Disease in dogs. It is a quick and simple procedure that can be performed at most veterinary clinics and specialty or emergency care facilities. 

Conclusion

When it comes to Addison's Disease, knowledge is power. By understanding the symptoms and causes of this serious condition, you can ensure that your pup gets the help they need. With the right combination of diet and lifestyle changes, medications, and supportive care, most dogs with Addison's Disease lead healthy and happy lives - all made possible with the guidance and support of a loving owner!