VCA Animal Hospitals

Addison's Disease in Dogs

What is Addison's disease?

Addison's disease is the common name for hypoadrenocorticism. Hypoadrenocorticism is a condition where there is diminished or lowered hormone production from the outer part or cortex of the adrenal gland.

What are the adrenal glands and what do they do?

addisons_disease-1The adrenal glands are small, paired glands located next to the kidneys. Each gland consists of an outer cortex and an inner medulla. The glands produce several substances that regulate a variety of body functions and are necessary to sustain life. The most widely known of these substances is cortisol, a corticosteroid commonly called cortisone or steroid, which is produced by the outer part of the adrenal cortex. Also produced by the adrenal cortex and equally important is aldosterone, which is a mineralocorticoid hormone. Aldosterone regulates the electrolyte and water balance of the body and is involved in the excretion of potassium and retention of sodium.

Deficiency of these two hormones, cortisol and aldosterone, is referred to as hypoadrenocorticism or Addison's disease.

What causes Addison's disease?

In the dog, the main causes are direct injury to the adrenal gland tissue, infection or certain autoimmune conditions. There are two main categories of Addison's disease, namely primary and secondary Addison's disease.

Primary hypoadrenocorticism results from a disease process in the adrenal glands; this may be caused by immune-mediated disease. It can also occur when treating Cushing's disease (hyperadrenocorticism), a disease in which too much cortisol and aldosterone are produced. Addison's disease may also result when a drug used to treat Cushing's disease, Lysodrenâ (mitotane) or trilostane, destroys too much of the adrenal tissues, resulting in a deficiency of cortisol and aldosterone.

Secondary Addison's disease results from a disease such as a tumor in the pituitary gland, which is an important hormonal regulator located in the brain. Secondary Addison's disease can also develop if a dog has been treated with long-term steroids for any reason and the medication is abruptly stopped. This is also known as iatrogenic hypoadrenocorticism.

What are the clinical signs of hypoadrenocorticism?

"Clinical signs of Addison's disease are usually vague and non-specific..."

Clinical signs of Addison's disease are usually vague and non-specific and are similar to the symptoms seen in animals with more common medical disorders such as chronic gastroenteritis or renal disease. Common signs include lethargy, diarrhea, vomiting, increased thirst and increased urination. Intermittent shaking episodes are also characteristic. The symptoms may wax and wane. Weight loss is often seen.

These animals will often improve with non-specific medical treatment. For example, the administration of fluids or corticosteroids appears to help temporarily, but the signs soon return. In a pet that experiences recurrent bouts of sudden lethargy, diarrhea and vomiting, increased thirst and urination or other non-specific illness, Addison's disease should be considered as an underlying cause.

What is an Addisonian Crisis?

Sometimes the condition takes on a much more serious form. There is sudden weakness, with severe vomiting and diarrhea, and sometimes the patient collapses. This is an Addisonian crisis and is considered a medical emergency. Under these circumstances, urgent hospitalization and supportive treatment will be necessary.

How is Addison's disease diagnosed?

Diagnosis is based on your pet's medical history and clinical signs, coupled with the results of blood and urine tests. The most common diagnostic tests are the ACTH-stimulation test and the low-dose dexamethasone suppression (LDDS) tests. Your dog will probably have to be admitted to the veterinary hospital for the day to perform the necessary tests. Additional tests such as radiographs or abdominal ultrasound are performed in suspicious cases or to rule-out another cause for your pet's clinical signs.

How is Addison's disease treated? 

addisons_disease_-_2_-_2009Once a diagnosis of hypoadrenocorticism has been made, most dogs can be successfully treated with oral medication. Your dog's diet and activity levels can often remain unchanged. The majority of dogs resume normal lives, even after an Addisonian crisis.

It will be necessary to monitor progress carefully, particularly at the start of treatment. This may involve occasional hospitalization for monitoring and follow-up testing.

It must be emphasized that lifelong replacement of both glucocorticoids (cortisol) and mineralocorticoids (aldosterone) may be necessary. Some of these medications, especially corticosteroids, may have to be increased during periods of stress, such as when traveling, if your dog is going to be boarded, or if your dog has to undergo surgery. In addition, your veterinarian will have to see your pet at regular intervals to ensure that stabilization is satisfactory. This usually involves simple follow-up blood and urine tests and routine ACTH-stimulation tests or LDDS tests.

What is the prognosis for a dog diagnosed with Addison's disease?

The vast majority of patients with Addison's disease have a good to excellent prognosis once the diagnosis has been established and they have been stabilized with the appropriate drugs. If you wish to discuss the long-term prognosis for your pet, please do not hesitate to contact your veterinarian.

Related Tags

addison, adrenal, hypoadrenocorticism, aldosterone, cortisol, gland, cortex, outer, prognosis, vomiting, addisonian, diarrhea, hormone, cushing, lethargy, urine, thirst, urination, acth-stimulation, corticosteroids, ldds, diet

Looking to learn more?

We also offer free, instant access to over 1,500 related articles on your pet's health including preventive medicine, common and not so common diseases, and even informative case studies. We encourage you to read any of these popular articles below or search our extensive pet health library.

Most Popular Articles

About our approach to exceptional pet health care

At VCA Animal Hospitals, our veterinarians take you and your pet's health seriously. With over 600 hospitals and 1,800 fully qualified, dedicated and compassionate veterinarians, we strive to give your pet the very best in medical care. We understand your pet is an extension of you, and appreciate the opportunity to share in providing exceptional pet care and quality of life.

* Free initial health exam for new clients only. Not to be combined with any other offer. Not good toward boarding, grooming, prescription and non-prescription medication, and retail items. Not good toward emergency and/or specialty veterinary services. Coupon good for up to two pets (dogs or cats only) per household. Redeemable only at a general practice VCA Animal Hospital. For pet owners who are aged 18 and older.

If you are a new client, you can get a free first exam* on your first visit.

Free First Exam

Get to know us by visiting one of our neighborhood hospitals.

Locate a Hospital

General Practice

We have over 540 animal hospitals in 41 states that are staffed by more than 2,000 fully qualified, dedicated and compassionate veterinarians, with more than 200 being board-certified specialists. The nationwide VCA family of general practice hospitals give your pet the very best in medical care, providing a full range of general medical and surgical services as well as specialized treatments*: Wellness, Spay/neuter, Advanced diagnostic services (MRI/CT Scan), Internal medicine, Oncology, Ophthalmology, Dermatology, Cardiology, Neurology, Boarding, Grooming

*services may vary by location.

Our family of pet hospitals stands out by delivering the greatest resources in order provide the highest quality care available for your pets. By maintaining the highest standards of pet health care available anywhere, we emphasize prevention as well as healing. We provide continuing education programs to our doctors and staff and promote the open exchange of professional knowledge and expertise. And finally, we have established a consistent program of procedures and techniques, proven to be the most effective in keeping pets healthy.

Find a VCA General Care Animal Hospital near you:


See all VCA Animal Hospitals >


Specialty Care

Sometimes sick or injured pets need the care of a veterinary medical specialist. When that happens, VCA specialty hospitals work closely with the general practitioner veterinarians who refer cases to us in order to provide seamless veterinary care to your pet. When your pet is facing any kind of serious illness or injury, our specialty referral hospitals will provide the compassionate and expert care your beloved pet needs.

Our goal is to make sure that when you and your pet are in need that you have access to board certified specialists who are up to date on the very latest developments in their field. In our state of the art hospitals, our specialists also have access to the most sophisticated diagnostic and treatment tools and techniques from ultrasonography and endoscopy to CAT scans and even MRI.

We have twenty-eight specialty hospitals across the US so there may be one near you. Our specialized services include: cardiology, critical care, dentistry, dermatology, internal medicine, neurology, oncology, ophthalmology, radiology and surgery.

Find a VCA Specialty Care Animal Hospital near you:


See all VCA Animal Hospitals >


Emergency Care

In case of emergency, please call us immediately. If it is after hours, check with a local animal hospital emergency clinic.