Common Symptoms of Addison's Disease in Dogs

Addison’s disease in dogs, also called canine hypoadrenocorticism, is a disease of the adrenal glands. It’s a serious condition in dogs, but often overlooked because the signs can be inconsistent and vague. Keep reading to find out why Addison’s disease is nicknamed “the great pretender.”

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What is Addison’s disease in dogs?

Hypoadrenocorticism, commonly called Addison’s disease, is a condition in which a dog’s adrenal glands don’t produce enough steroid hormones — specifically cortisol and aldosterone. This shortage causes dogs to be unable to respond appropriately to stress or to regulate their blood sugar or electrolytes properly. 

Dogs have two adrenal glands, one located near each kidney. The adrenal glands produce corticosteroids and mineralocorticoids. Cortisol, a corticosteroid, helps regulate multiple bodily functions such as blood pressure, blood sugar, metabolism, inflammation, and the sleep-wake cycle. Cortisol is also released in times of stress, providing the body with an extra energy boost. Aldosterone, a mineralocorticoid, is essential for regulating blood pressure and maintaining sodium and potassium (electrolyte) levels. 

Addison’s disease leads to insufficient levels of cortisol and aldosterone, hindering a dog’s ability to maintain their blood sugar, blood pressure, energy, and electrolyte levels. Addison’s disease tends to occur in middle-aged dogs, and it may occur more frequently in female dogs.

There are two types of Addison’s disease in dogs: typical (more common) and atypical. Dogs with typical Addison’s disease are deficient in both cortisol and aldosterone. Atypical Addison’s disease occurs when a dog is only deficient in cortisol. 

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Common symptoms of Addison's disease in dogs

The signs of Addison’s disease in dogs are infamously non-specific and vague, earning the condition the nickname, “the great pretender.” Symptoms can wax and wane for months, and they may only appear after a dog undergoes a stressful event like traveling or boarding. Early symptoms of Addison’s disease in dogs include: 

• Lethargy

• Vomiting

• Diarrhea (sometimes bloody)

• Anorexia

• Increased thirst

• Increased urination

• Weakness

• Weight loss

Addisonian crisis

A dog that is experiencing mild to moderate symptoms can often recover with rest or general supportive care like fluid therapy and anti-nausea medication. However, over time, symptoms can increase in severity to the point that they’re life-threathing — a condition called an Addisonian crisis. An Addisonian crisis causes a dog to be in shock with severe electrolyte abnormalities that require immediate emergency treatment. Signs can include:

• Collapse

• Pale gums

• Bloody diarrhea

• Abdominal pain

• Vomiting

• Low body temperature

• Low heart rate

• Weak pulses

Causes and risk factors of Addison's disease

Most cases of Addison’s disease are idiopathic, meaning we don’t know the exact reason it occurred. But there are known risk factors and causes of Addison’s disease in dogs that can aid with diagnosis:

Auto-immune disorder

Immune-mediated destruction of the layers of the adrenal glands is assumed to be the most common cause of canine Addison’s disease. 

Genetic factors

There is a genetic risk factor as some dog breeds are predisposed to the immune-mediated dysfunction that lead to hypoadrenocorticism. Breeds with increased risk include:

• Standard Poodle

• Portuguese Water Dogs

• West Highland Terriers

• Rottweiler

• Great Dane

• Bearded Collie

• Wheaten Terrier

• Nova Scotia Duck Tolling Retriever

Adrenal damage

Although immune-mediated damage is the most common cause of adrenal damage, other conditions can cause damage to the adrenal glands and lead to dysfunction. These include cancer, trauma, infection, bleeding, and decreased blood supply to the glands. 

Abrupt withdrawal of long-term steroids

Dogs that are treated long-term with steroids like prednisone or dexamethasone may develop adrenal atrophy over time. The adrenal glands atrophy because the medications provide the steroids they usually produce. However, if steroids are stopped abruptly, the adrenal glands may not be able to ramp up production of cortisol quickly enough, leading to Addison’s disease. 

Other medications

Dogs with hyperadrenocorticism, commonly called Cushing’s disease, are often treated with medications that will lower the production of cortisol by the adrenal glands. If the dosage is too high or a dog’s response to the medication is not monitored, the medication can suppress adrenal function too much, leading to hypoadrenocorticism. 

How Addison’s disease is diagnosed

Because of the ambiguous nature of the symptoms of Addison’s disease, diagnosis is often made during an Addisonian crisis. Sometimes veterinarians or astute dog parents will recognize a pattern of symptoms linked to stressful events, putting the disease on their radar. So, a dog’s medical history and physical exam findings are helpful. These tools are how vets diagnose Addison’s disease in dogs:

ACTH stimulation test

An ACTH stimulation test is considered the gold standard when it comes to diagnosing Addison’s disease. ACTH is a hormone produced by the brain that triggers the adrenal glands to produce cortisol. During an ACTH stimulation test, a blood sample is collected to measure a dog’s baseline cortisol level. Then, the dog is given a dose of synthetic ACTH to “stimulate” the adrenal glands. After an hour, a second blood sample is taken and the cortisol level again. 

A dog with normal adrenal function will show a spike in their cortisol level. A dog with Addison’s disease, on the other hand, will continue to have a low cortisol level because the adrenal glands didn’t respond to the stimulation.

Blood work

A standard chemistry panel and complete blood profile won’t provide a definitive diagnosis, but they can reveal changes that raise suspicion and provide information on how the disease is affecting the dog. Commonly seen abnormalities include electrolyte imbalances, elevated kidney enzymes, low protein levels, and low blood sugar. Dogs with atypical Addison’s disease will have normal electrolytes.

Ultrasound

Abdominal ultrasound is not typically used to diagnose Addison’s disease, but a veterinarian may notice small adrenal glands in a dog with the condition.

Treatment options for Addison’s disease

The initial treatment for Addison’s disease in dogs depends on the severity of the symptoms at the time of diagnosis. Because many dogs are diagnosed due to an Addisonian crisis, initial treatment can involve stabilization and hospitalization for:

• IV fluid therapy

• Glucose supplementation

• Steroid supplementation

• Antinausea medication

• Stomach protectants

• Electrolyte adjustment and monitoring

• ECG monitoring

After initial stabilization, dogs are started on long-term treatment, which normally consists of a combination of oral medication and monthly injections. Oral steroids, like prednisone, can be given to replace cortisol. An injectable drug called desoxycorticosterone pivalate (DOCP) can be administered monthly to replace aldosterone. 

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How to manage Addison’s disease in dogs

The prognosis for dogs with Addison’s disease is good with proper treatment and management; however, the condition requires lifelong treatment. If your dog has been diagnosed with hypoadrenocorticism, here are some tips to help prevent future crises:

Stick to a consistent medication schedule

Establish a routine to ensure that medications are given consistently and no doses are missed. Schedule appointments for monthly DOCP injections in a timely manner to avoid scrambling to get an appointment at the last minute.

By the way: I’ve seen more than one Addisonian dog on an emergency basis just for DOCP injections because their parents couldn’t get in to see their primary vet. I’m sure ER injections are way more expensive.

Schedule routine vet checkups

Medication doses may need to be adjusted over time, especially in the first months after initial diagnosis. Regular check-ins and blood work are recommended to monitor your dog’s response to the medications.

Prepare for stressful events

Talk to your vet if your dog is about to encounter a known stressor, like travel, boarding, or fireworks. Your vet may recommend a temporary dose adjustment. 

Watch for early signs of an Addisonian crisis

Watch for signs that can be seen in a crisis like vomiting, diarrhea, weakness, or shaking. If your dog seems extremely lethargic or collapses, seek treatment right away. 

Bottom line: Addison’s disease in dogs

Addison's disease in dogs can cause vague symptoms like lethargy, vomiting, and weight loss that can progress to a life-threatening crisis. Although hypoadrenocorticism is a serious disease, its prognosis is good with timely diagnosis, effective treatment, and proper management.

References

• Baumstark, M.E., et al. “Evaluation of Aldosterone Concentrations in Dogs with Hypoadrenocorticism.” Journal of Veterinary Internal Medicine, vol. 28, no. 1, 15 Nov. 2013, pp. 154–159, https://doi.org/10.1111/jvim.12243.

• Cohn, Leah, and Etienne Cote. Cote's Clinical veterinary Advisor: Dogs and Cats - E-Book. Elsevier eBooks+, (4th Edition). Elsevier - OHCE, 2019.

• John Hopkins Medicine. “Adrenal Glands.” John Hopkins Medicine, www.hopkinsmedicine.org/health/conditions-and-diseases/adrenal-glands.

• Van Vertloo, Laura. “Addison Disease (Hypoadrenocorticism) in Animals.” MSD Veterinary Manual, MSD Veterinary Manual, July 2024, www.msdvetmanual.com/endocrine-system/the-adrenal-glands/addison-disease-hypoadrenocorticism-in-animals.