Last Updated on May 16, 2026 by admin
Addison’s disease in dogs is a veterinary condition, not a home-diagnosis problem. It happens when the adrenal glands do not make enough essential hormones, and the signs can look vague at first: low energy, vomiting, diarrhea, poor appetite, weight loss, weakness, shaking, increased thirst, or episodes that seem to improve and then return. A dog who collapses, is very weak, has repeated vomiting or diarrhea, or seems shocky needs urgent veterinary care.
The old version of this article mixed Addison’s disease with signs more typical of other endocrine problems, including diabetes or Cushing’s disease. That matters because Addison’s can become an Addisonian crisis, a medical emergency that usually needs prompt fluids, bloodwork, and hormone support from a veterinarian.
What Addison’s Disease Means in Dogs
Addison’s disease is also called hypoadrenocorticism. In many dogs, the adrenal glands do not produce enough cortisol and, often, aldosterone. Cortisol helps the body respond to stress and maintain normal metabolism. Aldosterone helps regulate sodium, potassium, and fluid balance.
When those hormones are too low, a dog may not maintain normal blood pressure, hydration, blood sugar, or electrolyte balance. That is why Addison’s can look like a stomach upset one week and an emergency collapse the next.
Common Signs to Watch For
Addison’s disease is sometimes called a great pretender because its signs overlap with many other illnesses. Possible signs include:
- Unusual tiredness, weakness, or exercise intolerance
- Poor appetite or refusing food
- Vomiting, diarrhea, or intermittent stomach upset
- Weight loss or poor body condition
- Shaking, trembling, or seeming unable to settle
- Increased thirst or urination in some dogs
- Slow heart rate, dehydration, or low blood pressure found on exam
- Episodes that improve with supportive care, then return
Increased appetite and a pot-bellied appearance are not the classic pattern for Addison’s disease. Those signs can fit other conditions, including Cushing’s disease, diabetes, medication effects, diet changes, or other medical problems. A veterinarian needs to sort out the cause with an exam and testing.
Emergency Signs
An Addisonian crisis can be life-threatening. Go to an emergency veterinarian or call your veterinary clinic right away if your dog has collapse, extreme weakness, pale gums, repeated vomiting or diarrhea, bloody diarrhea, severe dehydration, a very slow or very fast heart rate, trouble standing, or a sudden decline.
If your dog collapses, keep them calm and safe during transport and review basic collapsed dog first aid while you contact an emergency clinic. Do not give human medications, force water, start supplements, or try to correct electrolytes at home unless a veterinarian gives specific instructions.
How Veterinarians Diagnose It
Your veterinarian may suspect Addison’s disease from the history, physical exam, and screening bloodwork. Many dogs have electrolyte changes, dehydration, low blood sugar, kidney-value changes related to dehydration, or a stress pattern that does not fit how sick they look. Some dogs have atypical Addison’s disease and may not show the classic sodium and potassium changes.
The ACTH stimulation test is commonly used to confirm Addison’s disease. It checks whether the adrenal glands can respond appropriately to stimulation. Your veterinarian may also recommend urine testing, imaging, heart rhythm checks, or additional tests to rule out other causes of vomiting, diarrhea, weakness, and weight loss.
Treatment and Long-Term Outlook
Treatment depends on whether the dog is stable or in crisis. A sick or collapsed dog may need hospitalization, intravenous fluids, electrolyte correction, and injectable medications. Stable dogs are usually managed with long-term hormone replacement and scheduled monitoring.
Many dogs with Addison’s disease do very well once diagnosed and treated, but the plan is individualized. Medication type, recheck timing, stress-dose instructions, and bloodwork monitoring should come from the veterinarian managing the case. Do not adjust steroid or mineralocorticoid medication without veterinary guidance.
What Not to Do at Home
- Do not assume vomiting, diarrhea, or weakness is just a minor stomach bug if it keeps returning.
- Do not use home electrolyte mixes, sports drinks, salt, sugar, or supplements as treatment.
- Do not give leftover steroids or stop prescribed steroids suddenly without veterinary direction.
- Do not wait for collapse before asking about Addison’s if your dog has repeated vague illness.
Vomiting and diarrhea can dehydrate dogs quickly, especially when an endocrine condition is involved. If bloody diarrhea or repeated vomiting is part of the picture, this can overlap with other urgent conditions such as AHDS/HGE, so a guide to bloody diarrhea and vomiting in dogs may help you recognize when the situation is urgent.
When to Call Your Vet
Call your veterinarian if your dog has recurring lethargy, poor appetite, vomiting, diarrhea, weight loss, shaking, increased thirst, or unexplained weakness. Ask whether Addison’s disease belongs on the rule-out list, especially if symptoms come and go or routine treatment only helps temporarily.
Seek urgent care now if your dog cannot keep water down, seems dehydrated, or is too weak to stand normally. You can also review dog dehydration red flags, but do not let a home checklist delay veterinary care for a dog who is rapidly worsening.