HYPO ADRENOCORTICISM

Breed predisposition 

• Standard Poodle 

• West Highland White Terrier 

• Bearded Collie 

• Great Dane 

• Portuguese Water Dog  

• Labrador Retriever 

• Rottweiler 

• Wheaten Terrier

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Cause 

• The adrenal glands produce hormones, including glucocorticoid (cortisol) and mineralocorticoid (aldosterone). These hormones regulate essentials functions including

  • Mineralocorticoids- electrolytes, blood pressure, hydration

  • Glucocorticoids- metabolism and stress responses.  

• The most common cause of Addison’s disease is auto-immune in nature.

• Less common causes of the disease could come from infection, cancer of the adrenal glands, over-medication during the treatment of Cushing’s disease (hyperadrenocorticism) or abruptly discontinuing steroids after long-term use.  

• Addison’s disease is considered “atypical” when only the cortisol hormone is affected, but not aldosterone, which means that the dog’s sodium and potassium electrolytes remain unaffected.   

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Clinical signs 

Addison’s disease is known as “the great pretender” because its clinical signs can mimic those of many other diseases.  

The signs can wax and wane, or be vague and non-specific, and they can include any of the following:  

• Lethargy 

• Loss of appetite 

• Vomiting 

• Diarrhea 

• Weight loss  

• Increased thirst and urination 

• Trembling 

• Weakness 

• Dehydration  

Addison’s disease can also present as an acute medical emergency called an Addisonian crisis. An Addisonian crisis may appear as sudden weakness, severe vomiting, diarrhea and sometimes collapse. If your dog shows any of these signs, they need immediate veterinary care.  

Diagnosis 

• Addison's disease is confirmed with ACTH Stimulation test.

• ACTH is a hormone that instructs the adrenal gland to produce cortisol. The test evaluates the adrenal gland’s response to a synthetic form of ACTH by measuring cortisol levels before and after the injection. 

• Normal post stimulation cortisol level is >10mcg/dl but in addison's its <2mcg/dl.

• Occasionally, tests such as X-rays or abdominal ultrasounds may be performed to rule out other causes of illness.  

Treatment 

• Typical forms of Addison’s disease require lifelong cortisol and aldosterone supplementation.  

• Cortisol is supplemented with daily oral steroids, such as prednisone.

• Aldosterone is supplemented with oral Fludrocortisone daily or with an injection, such as Percorten or Zycortal, about once per month.

• An oral medication called Florinef may be used to replace both aldosterone and cortisol.  

• Treatment during an acute Addisonian crisis may include IV fluids and other IV medications such as glucose, medications to protect the GI tract and glucocorticoids after performing diagnostic tests.

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