Addisons Disease in Dogs

Addison's disease is usually caused by damage to the adrenal cortex, which leads to too little cortisol and often too little aldosterone. In many dogs, the most likely cause is immune-mediated destruction of adrenal tissue. Less common causes include infection, cancer affecting the adrenal glands, complications from treatment for Cushing's disease, pituitary disease causing secondary hypoadrenocorticism, or abrupt withdrawal after long-term steroid use.

Risk factors and patterns seen in dogs include: • Breed predispositions reported in veterinary sources, including Standard Poodles, Portuguese Water Dogs, Bearded Collies, Nova Scotia Duck Tolling Retrievers, Leonbergers, Great Danes, and Labrador Retrievers. • Addison's is uncommon overall, which can make diagnosis slower because signs resemble many other illnesses. • Dogs may have classic Addison's disease with electrolyte changes, or atypical Addison's disease in which cortisol is low but sodium and potassium may stay normal. • Signs often wax and wane, so owners may notice periodic stomach upset, weakness, or "not acting right" episodes before diagnosis.

Diagnosis usually starts with a full history, physical exam, and baseline lab work. Your veterinarian will typically run bloodwork and a urinalysis to look for clues such as sodium and potassium abnormalities, dehydration, kidney-related changes, or other conditions that can mimic Addison's disease.

Tests and next steps may include: • CBC, chemistry panel, and urinalysis. • Electrolyte testing, especially sodium and potassium. • A resting cortisol test, which can help rule out Addison's when it is above the usual cutoff used in veterinary medicine. • ACTH stimulation test, which is the confirmatory test used to diagnose Addison's disease. • Additional tests in some dogs, such as ECG, abdominal imaging, endogenous ACTH testing, or advanced imaging if secondary disease is suspected.

At the appointment, your vet may also ask about prior steroid use or treatment for Cushing's disease, because these can affect the adrenal glands and change the diagnostic plan.

Treatment depends on whether your dog is stable or in an Addisonian crisis. Dogs in crisis need emergency hospital care for IV fluids, close monitoring, and hormone support. Once stable, most dogs do very well with lifelong hormone replacement and regular follow-up testing.

Common treatment approaches include: • Mineralocorticoid replacement for dogs that need aldosterone support, often with desoxycorticosterone pivalate (DOCP) injections or, in some cases, oral fludrocortisone. • Glucocorticoid replacement for cortisol deficiency, commonly with long-term oral steroid therapy prescribed by the veterinarian. • Routine electrolyte monitoring to adjust the injection interval or medication plan safely. • Stress-dose planning directed by your veterinarian before major illness, surgery, boarding, or other stressful events. • Emergency treatment right away if there is collapse, shock, severe vomiting, or severe diarrhea.

Most dogs can keep a normal diet and activity level once treatment is stabilized. Because this is a lifelong condition, regular rechecks with your veterinarian are a key part of successful management.