Addison's disease (hypoadrenocorticism) is a life-threatening adrenal insufficiency in dogs that causes episodic crises of extreme weakness and collapse, often going undiagnosed for months due to its highly variable presentation.
Addison's disease causes episodic suffering that is particularly cruel because of its unpredictability. Dogs experience repeated crises of profound weakness, nausea, and cardiovascular instability that may be triggered by any physical or psychological stressor. Between crises, they may appear normal - making diagnosis challenging. The Addisonian crisis itself involves rapid deterioration with severe vomiting, collapse, and the physiological experience of cardiovascular shock. Because Addison's is often called 'the great pretender' due to its variable presentation, many dogs are misdiagnosed repeatedly before the correct diagnosis is made, extending the period of episodic suffering. Once diagnosed and managed, the transformation in quality of life is dramatic.