The condition begins right at the pituitary gland. This gland is responsible for producing adrenocorticotropic hormones, or ACTH for short. ACTH then makes its way into the adrenal glands and stimulates them.

• Cortisol. Regulates metabolism, stress response, and immune function.

• Aldosterone. Regulates blood pressure, electrolyte balance, and fluid balance.

In hypoadrenocorticism, affected dogs will have trouble maintaining normal physiological functions. This can be potentially severe and life-threatening.

What Are the Symptoms of Addison's Disease in Dogs​

The condition is often called “The Great Imitator” in dogs because it mimics other diseases through its general symptoms. However, the disease can progress to more deadly symptoms over time. 

• Lethargy or weakness. Lethargy is often the first and most common symptom of canine Addison’s disease. Affected dogs may sleep more often and choose to rest rather than play. 

• Loss of appetite. Affected dogs may not eat at all. Even when given their favorite meals and treats, they’ll have no appetite, sometimes refusing food.

• Vomiting and diarrhea. Due to the severe lack of cortisol and aldosterone, dogs may experience significant gastrointestinal inflammation, fluid imbalances, and blood pressure drops. These lead to vomiting and diarrhea. 

• Increased thirst and urination. Although less common, some dogs exhibit polydipsia and polyuria. You’ll often see your dog quickly finishing its water bowl and making frequent trips to pee. 

• Weight loss. Because of the lack of appetite, dogs will lose a significant portion of their weight. This is also due to inefficient nutrient absorption. 

• Muscle tremors. Muscle tremors or visible shaking often result from imbalances in potassium and sodium levels. These electrolytes are crucial for normal muscle function and nerve signals. 

• Irregular heart rate. An irregular heart rate can also be expected due to electrolyte imbalances, specifically high levels of potassium. 

• Sudden collapse. In severe cases, dogs will suddenly become weak and collapse. They might be unable to stand and move. 

Are There Complications of Addison’s in Dogs?

Addison’s disease in dogs can progress to more severe health issues, including: 

• Addisonian Crisis. This occurs when the condition is left untreated and leads to a sudden worsening of symptoms, including collapse and weakness. 

• Severe Cardiovascular Issues. Excessive potassium levels can lead to a slower heart rate and arrhythmias. 

• Kidney Damage. Untreated Addison’s can cause kidney damage. 

• Gastrointestinal Distress. Possible severe vomiting and diarrhea, often with bloody stools.

• Hypoglycemia. Excessively low blood sugar, caused by cortisol deficiency. 

What Causes Addison’s Disease in Dogs?

Addison’s in dogs can be caused by primary and secondary factors. Primary factors directly affect the adrenal glands, while secondary causes involve another part of the body, resulting in a domino effect on the adrenal glands. 

Autoimmune Disease

The most common cause of Addison’s disease is autoimmune adrenalitis. This is when the dog’s immune system mistakenly targets and attacks the adrenal glands. Because of this, dogs will lose essential hormones. 

The damage is also permanent, which means affected dogs will need lifelong management and care. 

Adrenal Gland Destruction 

Canine Addison’s disease can also be caused by adrenal gland destruction brought about by infections, trauma, and tumors. 

• Infections. When bacterial or fungal infections worsen, they can potentially reach the adrenal glands and severely damage the tissues. 

• Trauma. Blunt force trauma to the abdomen can directly affect the adrenal glands. 

• Cancer. Abnormal growths in the adrenal glands can destroy adrenal tissue, directly hindering hormone production.

Medications

Medications, such as corticosteroids, can also impair the function of the adrenal glands. They can essentially suppress the natural function of the adrenal glands, causing canine Addison’s disease. This often happens with long-term steroid use. 

Additionally, the medicines for Cushing’s disease in dogs, the opposite of Addison’s, can also suppress adrenal function. 

Secondary Causes

In rare cases, Addison’s in dogs can be caused when the pituitary gland fails to produce ACTH. This may happen due to trauma to the head or tumors on the pituitary gland. Secondary Addison’s may also be caused by abruptly stopping long-term corticosteroid medication. 

Idiopathic Reasons

In some cases, dogs may experience Addison’s disease without a known cause.