OldieAddison's disease, or hypoadrenocorticism, is the mirror of Cushing's: the adrenal glands make too little cortisol and often too little aldosterone. It is uncommon, with a reported prevalence in Europe of well under 0.1 percent, and it affects females more than males12. In a Swedish insured population the incidence was nearly twice as high in females, and breed differences were clear, with the Standard Poodle and the Golden Retriever among the breeds studied2.
It is called the great pretender because the signs come and go: bouts of vomiting, diarrhoea, lethargy, poor appetite, shaking and weakness, often worse after stress. An Addisonian crisis, with collapse and a slow heart rate, is an emergency. Diagnosis is a stimulation test, and treatment is lifelong hormone replacement, usually a monthly injection plus daily tablets, monitored with blood tests; AAHA's 2023 endocrine guidelines describe the approach3.
Dogs on treatment live normal lives, but doses must not be missed and stress may call for a temporary increase, so put the injection date and daily tablets on Oldie's schedule and note any illness in the care history.
This is general information, not a diagnosis. Your vet knows your dog.
Sources
- Hypoadrenocorticism in dogs under UK primary veterinary care: frequency, clinical approaches and risk factors (Schofield I et al.). Journal of Small Animal Practice 62(5):343-350, 2021 (peer reviewed). Accessed 2026-09-22.
- Naturally occurring adrenocortical insufficiency: an epidemiological study based on a Swedish-insured dog population of 525,028 dogs (Hanson JM et al.). Journal of Veterinary Internal Medicine 30(1):76-84, 2016 (peer reviewed). Accessed 2026-09-22.
- 2023 AAHA Selected Endocrinopathies Guidelines: Canine Hypoadrenocorticism (Addison's disease). American Animal Hospital Association. Accessed 2026-09-22.