Everything you need to know about Addison’s disease in dogs

Addison’s disease in dogs occurs when either the pituitary gland or adrenal glands are not functioning properly. Clinical signs are often vague and come and go on their own, making the condition difficult to diagnose. Even if the symptoms are mild and intermittent, it’s important for pet parents to be aware of the signs and talk to a veterinarian. Read on to learn:

• What is Addison’s disease and how does it affect dogs?
• How do I know if my dog has Addison’s disease or an Addisonian crisis?
• What causes canine Addison’s disease?
• How is Addison’s disease in dogs diagnosed and treated?
• Can I prevent my dog from getting Addison’s disease?

Addison’s disease in dogs is often mistaken for more common diseases until an Addisonian crisis occurs. A crisis is life-threatening, causing severe symptoms such as low blood pressure, collapse, seizures, and pale gums. Due to the vague and intermittent symptoms of Addison’s disease, many cases are not definitively diagnosed until a crisis occurs and the odds for successful treatment are much lower. However, dogs with well-managed Addison’s disease can live a normal life.

The medical term for Addison’s disease is hypoadrenocorticism, meaning the adrenal glands are not producing an adequate level of stress hormones. This disorder can be very difficult to diagnose due to intermittent and vague symptoms that mimic other conditions and come and go regardless of treatment. There are two types of Addison’s disease.

• Primary: The adrenal glands do not produce enough cortisol and aldosterone.
• Secondary: The pituitary gland doesn’t produce enough of the hormone that stimulates adrenal gland activity. As a result, cortisol and aldosterone levels drop.

Addison’s disease is uncommon in dogs, and primary Addison’s is the most common form. However, the secondary form is beginning to occur with increasing frequency. Both forms are progressive and require lifelong treatment.

What do the pituitary and adrenal glands do?

The stress hormones cortisol and aldosterone are produced by the adrenal glands and are essential for life-sustaining functions such as maintaining:

• Electrolyte levels
• Blood pressure
• Hydration
• Metabolism
• Stress response

Among other functions, the pituitary gland produces adrenocorticotropic hormone (ACTH), which stimulates the adrenal glands to produce cortisol. Addison’s disease can occur if either of these glands are damaged or functioning improperly.

Clinical signs of Addison's disease are often vague and intermittent early in the course of the illness, meaning the symptoms don’t point to any specific disease and come and go over time. Symptoms may include:

• Lethargy
• Vomiting or diarrhea
• Increased thirst
• Weakness
• Loss of appetite
• Hair loss
• Weight loss
• Abdominal pain
• Dehydration

These vague symptoms mimic a wide range of other, more common health conditions, such as gastrointestinal disease. In fact, Addison’s disease is nicknamed “the great imitator” or “great pretender” because of this. Symptoms typically go away on their own at first, before progressing and becoming more severe over time.

“Dogs with Addison’s often go a long time without being diagnosed because their symptoms can be attributed to something else like a simple upset stomach,” explains Dr. Jo Myers, a veterinarian on the Vetster platform. “Additionally, early symptoms tend to resolve on their own, but Addison’s disease is progressive and the symptoms eventually get worse, potentially leading to an Addisonian crisis.”

What does an Addisonian crisis look like?

An Addisonian crisis occurs when there is a decrease in blood volume due to prolonged low adrenal hormone levels. The symptoms are sudden, severe, and life-threatening. Symptoms of an Addisonian crisis include:

• Collapse
• Pale gums
• Weak or irregular heart rate
• Cold extremities
• Bloody diarrhea
• Seizures

It’s important for dog owners to get in touch with a veterinarian right away so they can get emergency treatment as quickly as possible if any of these symptoms occur. The survival rate of Addisonian patients in crisis is low and decreases if intensive care is not provided in a timely manner.

How common is canine hypoadrenocorticism?

Addison’s is an uncommon disease that mostly affects young to middle-aged dogs. Female dogs are at a slightly higher risk than males, though any dog can be affected. The condition is seen more often in certain breeds.

Addison's disease is caused by a lack of cortisol and aldosterone, but the decreased production can result from different causes. A genetic autoimmune response, infections, injuries, cancer, and inappropriate use of medications all have the potential to lower cortisol and aldosterone production and lead to Addison’s disease.

Genetics

Most cases of Addison’s result from an inherited trait that causes the dog's immune system to destroy its own adrenal tissue. Some breeds that are predisposed to Addison’s disease include:

• Standard poodles
• Great Danes
• Bearded collies
• Portuguese water dogs
• Labrador retrievers
• Pomeranians
• Wheaten, cairn, and West Highland white terriers
• Rottweilers

Other types of glandular damage

A variety of health issues can affect the glands regulating stress hormone production and trigger Addison’s disease. They include:

• Infection
• Adrenal gland cancer
• Lymphoma
• Injuries

A traumatic injury or tumor affecting the pituitary gland or adrenal glands can cause Addison’s disease. Blunt-force trauma to the head or abdomen from accidents, such as being hit by a car, can severely damage these glands and lead to lower levels of stress hormone production. Similarly, a tumor growing in the adrenal gland can destroy enough tissue to decrease stress hormone production. While it’s possible for a tumor in the pituitary gland to lower production of the hormone that stimulates the adrenal gland and lead to Addison’s disease, the most common pituitary tumors actually lead to increased production and cause Cushing’s disease instead.

Side effect of medication

Some medications alter how the adrenal glands work and can lead to Addison’s disease.

Steroids are commonly used for many diseases, and short-term relief of allergy symptoms is one of the most frequent reasons. When medicating your dog with a steroid, such as prednisone, it’s crucial to follow the instructions exactly and never suddenly stop medicating them. Gradually reducing the amount of steroids your dog receives allows the adrenal glands time to increase hormone production.

Mitotane and trilostane are medications used to treat dogs for Cushing’s disease, which is caused by excessively high levels of adrenal hormones — essentially the opposite of Addison’s disease. Since these medications treat Cushing’s by inhibiting cortisol production in the adrenal glands, they can potentially lead to abnormally low levels of cortisol. Because of the risks they pose, patients using these medications or using corticosteroids long-term are closely monitored for side effects.

Addison’s disease is notoriously difficult to diagnose early on due to vague symptoms and the lack of significant changes on routine blood tests. As a result, many cases are not diagnosed until an Addisonian crisis occurs. The diagnosis of hypoadrenocorticism prior to a crisis involves diagnostic testing to rule out other, more common causes of the presenting symptoms. Diagnosing hypoadrenocorticism may involve:

• Physical examinations
• Blood tests
• Urine tests
• Electrocardiogram heart tests
• X-rays or abdominal ultrasounds

Addison’s disease does not appear on routine blood tests, although some results may suggest it, such as abnormal sodium and potassium levels. Specific testing for Addison’s disease is more complicated and takes longer than routine testing, so it’s not usually performed unless Addison’s is suspected. Tests for Addison’s disease involve measuring baseline cortisol levels in the blood, giving an injection to stimulate adrenal gland activity, and then remeasuring cortisol levels in a second blood sample. Cortisol concentrations in dogs with Addison’s disease do not increase, while dogs without the condition have elevated cortisol in response to the injection.

Clinical signs of an Addisonian crisis, including collapse, loss of consciousness, shock, low blood pressure, low body temperature, and low blood glucose levels, are medical emergencies and must be treated immediately to save the dog’s life before specific diagnostic tests for Addison’s can be performed. There may be enough time for the veterinarian to give a steroid injection to a dog suspected of being in an Addisonian crisis, and if the suspicion is correct, the dog may start to quickly improve. If the dog survives and is stabilized, similar diagnostic tests are performed to rule out other causes of the symptoms and diagnose Addison’s disease.

For most affected dogs, long-term treatment involves hormone replacement medications to regulate cortisol and aldosterone levels. An oral medication is given at home, usually daily, and a trip to the vet is necessary every few weeks for an injection. In addition, cortisol and electrolyte levels must be closely monitored with blood tests. Weekly or biweekly veterinary visits may be required for the first few months of treatment until hormone levels are stable. Once the levels are deemed stable, this testing can usually be tapered down to every few months. Owners of dogs with Addison’s disease typically need to take their dog to the vet several times a year to keep their dog in stable condition.

A dog in an Addisonian crisis becomes severely ill, usually out of the blue, so initial treatment involves stabilizing the canine patient in the hospital. These treatments may involve:

• IV fluid therapy
• Correction of sodium and potassium levels
• Other supportive care for temperature, blood pressure, and blood sugar levels

Treatments for a crisis require hospitalization for fluid therapy, other symptomatic care, and close monitoring from veterinary staff. Once a crisis patient is stable enough to go home, long-term maintenance therapy can begin. The hormone replacement therapy needed for Addison’s disease is a lifelong treatment, and the associated costs are significant. However, dogs with well-managed Addison’s disease usually live a normal lifespan.

Addison’s disease in dogs is primarily caused by genetics and cannot be prevented. It’s important to avoid a life-threatening Addisonian crisis by pursuing intermittent digestive symptoms with a veterinarian and by closely monitoring a previously diagnosed dog during treatment throughout its life. Talking to a vet when your dog shows clinical signs of Addison’s disease can help catch the condition before a crisis occurs. These signs may include:

• Repeated bouts of vomiting or diarrhea
• Weight loss
• Lethargy
• Increased thirst or urination

It’s best to talk to a veterinarian when symptoms of adrenal insufficiency occur, even if they seem mild or go away after a few days. These clinical signs may point to Addison’s disease or another condition with similar symptoms.

The form of Addison’s disease that occurs when suddenly stopping steroid medications can be avoided by tapering the medications off gradually. Always follow the labeled instructions when giving prednisone or other steroid-containing medications, and keep track of your supply so you don’t run out and have to stop cold turkey. Dogs being treated for Cushing’s disease should also be monitored closely to avoid the form of Addison’s disease caused by Cushing’s medications.

Since Addison’s disease involves an imbalance of stress hormones, extremely stressful events can interfere with treatment. Stressful events are best avoided, but when they can’t be, you can talk to a veterinarian to learn what symptoms to watch for and discuss potential medication changes ahead of time.

Is my dog at risk for Addison’s disease?

Some dog breeds are genetically predisposed to developing Addison’s disease, and female dogs have a slightly higher risk. However, any dog can develop the condition. Addison’s disease is usually first diagnosed in dogs around four years of age.

It’s best to talk to a veterinarian any time you are worried about your dog’s symptoms or behavioral changes. You know your dog best, and slight changes may be more apparent to you than to a veterinarian. It’s important to voice your concerns and let them know of any changes you have observed in your dog at home. Addison’s disease is uncommon, and other health issues have similar symptoms. However, if you are concerned your dog has Addison’s disease, ask your veterinarian if diagnostic tests are recommended. If your dog is experiencing symptoms or if you would like to learn more about Addison’s disease in dogs, a veterinarian can talk to you in a virtual vet appointment through Vetster.

What is the life expectancy of a dog with Addison’s disease?

A dog with well-managed Addison’s disease usually has a normal lifespan and good quality of life. Management requires daily medication at home, as well as diligent visits to a veterinarian for recommended injections and blood tests.

What are the common symptoms of Addison’s disease in dogs?

Common symptoms include repeated bouts of vomiting or diarrhea, lethargy, and poor appetite, and these symptoms tend to go away without treatment. These symptoms may be mild, intermittent, and easy to overlook or mistake for other health problems. Symptoms of an Addisonian crisis include collapse, pale gums, a weak pulse, bloody diarrhea, cold extremities, and seizures. Not all dogs show every symptom of Addison’s disease or an Addisonian crisis.

How much does it cost to treat Addison’s disease in dogs?

Addison’s disease can be expensive to diagnose and treat due to daily prescription medications, regular veterinary visits, weekly injections provided by your vet, and repeated blood tests. Expenses can vary widely between dogs depending on how often they need testing, their medication dosage, and other factors.

Are dogs with Addison’s disease in pain?

A dog with well-managed Addison’s disease can live a normal, happy life. Symptoms of unmanaged Addison’s disease in dogs, such as vomiting, diarrhea, and lethargy, can be unpleasant, but may not be painful. However, severe and life-threatening clinical signs of an Addisonian crisis, such as collapse, seizures, pale gums, and bloody diarrhea, can cause severe pain and discomfort for dogs, and even with prompt veterinary treatment, the dog may not survive. It is important to maintain proper treatment with a vet to prevent an Addisonian crisis.