Addison disease involves adrenal gland insufficiency in dogs, causing life-threatening Addisonian crises if unmanaged but excellent quality of life with treatment.
Undiagnosed Addison disease causes repeated crises of severe weakness, vomiting, and collapse that are life-threatening and terrifying. Once diagnosed and treated, most dogs live fully normal lives with excellent quality. Dogs need stress dosing of glucocorticoids during illness or stress to prevent crisis - owner education is critical.