Addison Disease in Dogs

Addison disease in dogs can feel scary because the signs are often vague at first. One day your dog is a little tired or off their food, and the next day they might be vomiting or acting weak. As a veterinary assistant, I can tell you this is one of those conditions where getting the right diagnosis and starting treatment can be truly life-changing. With proper medication and monitoring, many dogs with Addison disease go on to live happy, active lives.

Note: This guide is for education and support and is not a substitute for veterinary care. If you are worried about your dog, please contact your veterinarian.

What is Addison disease?

Addison disease is the common name for hypoadrenocorticism. It happens when a dog’s adrenal glands do not make enough steroid hormones, mainly:

• Cortisol: helps the body respond to stress, supports blood sugar, and affects digestion and immune function.
• Aldosterone: helps regulate sodium and potassium balance and supports hydration and blood pressure.

When these hormones run too low, the body can struggle to maintain normal blood pressure, electrolytes, and energy levels. Symptoms can come and go for weeks or months, which is why Addison disease is sometimes called “the great pretender.” For example, a dog may have a few days of vomiting and low appetite, seem fine again, then relapse after boarding, travel, or another illness.

Why it happens

Primary Addison disease (most common)

This form happens when the adrenal glands are damaged, and it is most often thought to be immune-mediated. The end result is reduced production of cortisol and often aldosterone too.

Secondary Addison disease

This happens when the pituitary gland does not signal the adrenal glands properly, leading to low cortisol. Aldosterone may be normal in many secondary cases.

Iatrogenic Addison disease

This can occur after treatment for Cushing disease (hyperadrenocorticism), if the body’s steroid production becomes suppressed or is suddenly reduced. It can also happen after abrupt withdrawal of long-term steroid medications (for example, prednisone), which can cause secondary hypoadrenocorticism.

Which dogs are at risk?

Addison disease can occur in any dog, including designer mixes, but it is diagnosed more often in young to middle-aged dogs and, in some studies, is reported more frequently in female dogs.

Certain breeds appear predisposed (such as Standard Poodles, Portuguese Water Dogs, and others), but mixed-breed dogs can absolutely develop Addison disease too. If you have a doodle, a herding mix, or a rescue of unknown background, it is still worth keeping Addison on your radar if symptoms fit.

Common signs (and why they are confusing)

Addison disease often looks like many other illnesses, including stomach upset, pancreatitis, kidney disease, or “stress.” You might notice:

• Low energy, weakness, or exercise intolerance
• Reduced appetite or picky eating
• Weight loss
• Vomiting or diarrhea (sometimes on and off)
• Shaking, trembling, or appearing painful
• Increased thirst and urination in some dogs
• Slow heart rate in some cases (especially if potassium is high)

The symptoms may improve for a while and then return, especially after a stressful event like boarding, travel, surgery, or another illness.

Addisonian crisis

An Addisonian crisis is a medical emergency. It can happen when hormone levels and electrolytes drop to the point that a dog’s circulation and organ function are threatened.

Emergency signs

• Repeated vomiting and/or severe diarrhea
• Collapse, extreme weakness, or inability to stand
• Dehydration
• Signs of shock, such as pale gums, very weak pulses, mental dullness, or low body temperature

If you suspect a crisis, go to an emergency veterinarian immediately. Treatment typically includes IV fluids, electrolyte correction, and steroid support. Many dogs improve quickly once the right therapy is started.

Diagnosis

Diagnosis starts with a combination of history, exam, and lab work. Addison disease can show up on routine bloodwork, but it is not always obvious.

Clues your veterinarian may see

• Electrolyte changes such as low sodium and high potassium (classic Addison)
• Dehydration with lab patterns that do not match typical dehydration, such as not seeing the expected rise in total protein
• Low blood sugar in some dogs
• Elevated kidney values that may improve with fluids (can mimic kidney disease)

Helpful screening

In many clinics, a baseline cortisol is used as a quick screening or rule-out step. A normal baseline cortisol makes Addison disease unlikely. A low baseline cortisol does not confirm Addison on its own, but it is a common reason your veterinarian will recommend confirmatory testing.

The key test

The most common confirmatory test is the ACTH stimulation test. It checks whether the adrenal glands can produce cortisol appropriately when stimulated. In Addison disease, cortisol stays low.

Your veterinarian may also recommend additional tests to rule out look-alike conditions, especially if electrolytes are normal. You may hear this called atypical Addison disease, which typically means normal sodium and potassium at diagnosis. Some atypical cases can later develop electrolyte abnormalities over time, so follow-up monitoring still matters.

Treatment

Treatment depends on whether your dog needs both mineralocorticoid and glucocorticoid support, and whether they are stable or in crisis.

Long-term medications

• Mineralocorticoid replacement to support sodium, potassium, hydration, and blood pressure. Common options include DOCP injections or fludrocortisone tablets. DOCP is often given about every 25 to 30 days, but the schedule and dose are individualized based on lab results and how your dog feels.
• Glucocorticoid replacement (usually prednisone or prednisolone) in a low daily dose, adjusted to the minimum that keeps your dog feeling well.

Stress dosing (very important)

Dogs with Addison disease often need a temporary increase in their steroid dose during stressful events. Stress can include:

• Boarding or travel
• Grooming for anxious dogs
• Injury
• GI upset or other illness
• Surgery or dental procedures

Your veterinarian will tell you exactly how to adjust medications when stress hits. When in doubt, call and ask. It is better to be proactive than to risk a crisis.

Monitoring

Most dogs do very well once stabilized, but the first few months can require fine-tuning. Monitoring is usually more frequent early on, then spaces out once your dog is stable.

What monitoring looks like

• Regular recheck exams
• Bloodwork to track electrolytes (especially sodium and potassium)
• Adjusting DOCP injection timing or dose based on lab trends
• Watching for signs of over or under-medication

Signs your dog may need an adjustment

• Returning vomiting, diarrhea, or low appetite
• New weakness or shakiness
• Excessive thirst and urination
• Restlessness, panting, or behavioral changes after steroid adjustments

Bring a simple notebook or use your phone to track appetite, energy, stools, and medication timing. Those little details can help your vet make the best dosing decisions.

Daily life tips

Addison disease is a long-term condition, but day-to-day life can be very normal with a good routine. Prognosis is generally good with consistent medication, a solid stress plan, and regular monitoring.

• Keep meds consistent: give medications at the same time daily, and do not stop steroids abruptly unless directed by your veterinarian.
• Plan ahead: make sure you have refills before you run out, especially around holidays.
• Create a stress plan: ask your vet for written guidance on stress dosing and what to do if vomiting starts.
• Know what to do if a dose is missed: follow your vet’s instructions. In general, do not double up without guidance. If your dog vomits soon after a dose or cannot keep medications down, call your veterinarian promptly because this can escalate quickly in Addison dogs.
• Consider an ID: a tag that notes “Addison disease” can help in emergencies.
• Diet basics: there is no single “Addison diet,” but steady, digestible nutrition helps many dogs. If your dog has a sensitive stomach, ask about a veterinary GI diet or a carefully balanced home-prepared plan guided by a professional.

Encouragement matters: the diagnosis can feel heavy at first, but Addison disease is very manageable once you and your vet team dial in the right plan.

Questions to ask your veterinarian

• Does my dog have classic Addison or atypical Addison?
• Which medication plan do you recommend, and why?
• How often should we check electrolytes at the start?
• How often do you expect DOCP injections, and how will we decide the right schedule?
• What is my dog’s stress dosing plan, and when should I use it?
• What should I do if my dog misses a dose or vomits right after taking medication?
• What symptoms mean I should call right away or go to emergency?

Urgent care

Please do not “wait and see” if your dog has Addison disease and you notice any of the following:

• Repeated vomiting, especially if your dog cannot keep medications down
• Severe diarrhea or black, tarry stool
• Collapse or extreme weakness
• Signs of dehydration (tacky gums, sunken eyes)
• Unusual slow heart rate, pale gums, or trouble standing

Fast treatment saves lives in an Addisonian crisis, and many dogs bounce back beautifully with prompt care.

Bottom line

Addison disease in dogs is a hormone deficiency that can cause anything from mild, on-and-off stomach upset to a true emergency crisis. The good news is that once diagnosed, it is typically very treatable, and most dogs can enjoy an excellent quality of life. If your dog has recurring GI symptoms, unexplained weakness, or odd lab results that keep coming back, talk to your veterinarian about whether Addison disease should be ruled out. Your attentiveness is one of the best tools your dog has.