What is Addison’s disease (hypoadrenocorticism)?

Addison’s disease is where the adrenal glands fail to produce mineralocorticoid (aldosterone) and glucocorticoid (cortisol). Both of these hormones are crucial to life.

Immune mediated destruction of the adrenal glands is the most common cause of Addison’s disease. This form of disease is classified as primary hypoadrenocorticism and usually results in deficiencies of both glucocorticoids and mineralocorticoids. An atypical Addison’s has been reported, where only cortisol is deficient.

Secondary hypoadrenocorticism (caused by pituitary dysfunction), results in the deficiency of adrenocorticotropic hormone (ACTH). This is a very rare cause of canine hypoadrenocorticism and tends to result in cortisol deficiency only.

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How to recognise Addison’s disease

Addison’s disease can be difficult to identify, so being more aware of this condition is half the battle. Addison’s disease is a potentially life-threatening condition.

Clinical signs associated with the disease are non-specific, can wax and wane, and dogs can respond to non-specific therapy (e.g. intravenous fluids). Therefore this condition can be easily mistaken for other diseases (e.g. kidney disease, gastroenteritis including parvovirus infection, neuromuscular and metabolic diseases).

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The most common signs of Addison’s disease are:

	Almost all cases	Common	Less common
Clinical History	Inappetence	Weakness	Diarrhoea
	Lethargy	Vomiting	Weight loss
			Shivering/muscle stiffness
			Polyuria
			Polydipsia
Physical examination	Depression	Dehydration	Bradycardia
	Weakness		Hypothermia

Specifically, a lack of aldosterone causes abnormalities in the electrolyte balance of the patient. The lack of cortisol can result is weakness, gastrointestinal problems such as vomiting and diarrhoea, and weight loss.

A combination of general blood work, and a specific endorcrine test may need to be performed. The patient will then be prescribed a combination of medications which will replace the aldosterone and cortisol deficiencies. These medications need to be given for life. Well medicated dogs can go on to lead a relatively normal life.