Addison's Disease in Dogs: Causes, Symptoms, and Treatments

Addison's disease, or hypocorticism in dogs, is a disease caused by dysfunction of the adrenal glands. Symptoms vary, but are often dominated by lethargy and digestive signs. This canine condition benefits from specific and very effective treatment.

1. What is Addison's disease in dogs? Is it dangerous for dogs?

Addison's disease, or hypocorticism in dogs, is a pathology of the adrenal glands, resulting in hyposecretion of natural corticosteroids.

What are the adrenal glands? They are two small glands located in the abdomen above the kidneys. In their outer layer (cortex), they produce various molecules called corticosteroids:

• Mineralocorticoids like aldosterone, which contributes to the body's hydro-electrolyte balance (i.e., the amount of water and ions such as Sodium or Potassium)

• Glucocorticoids like cortisol, which have multiple roles (glucose regulation, stress response, anti-inflammatory)

• Androgens

The inner layer (medulla) secretes adrenaline and noradrenaline.

When the adrenals are overactive, it is called hypercorticism or Cushing's disease. In case of underactivity, it is hypocorticism or Addison's disease; cortisol and aldosterone levels plummet, leading to serious consequences for the dog and potentially endangering its life.

Did you know? This rare adrenal pathology can also affect humans and, exceptionally, cats. Thomas Addison (1793-1860), an English physician, first described it in 1855.

2. Causes: what are the causes of Addison's disease in dogs?

The main cause of Addison's disease or primary hypocorticism is an autoimmune condition: the dog's immune system itself destroys the cortical area of the adrenal glands.

More rarely, secondary hypocorticism can occur following the administration of certain medications for hypercorticism.

3. Are there dogs predisposed to hypocorticism?

Addison's disease in dogs is a rare pathology (<0.5%). Some breeds are reportedly predisposed: Poodle, Rottweiler, Collie, Westie. Females are also more often affected than males.

Generally, the disease appears in young animals, around 4-5 years of age on average.

4. Symptoms: what are the clinical signs of Addison's disease in dogs?

Clinical signs are a consequence of decreased cortisol and mineralocorticoids in the body. They include:

•       lethargy, hypotension

•       anorexia

•       vomiting and diarrhea (sometimes with digested blood)

•       weight and muscle loss

•       increased thirst and urination (polyuria-polydipsia)

•       dehydration

•       hypoglycemia, which can induce seizures or coma

•       shock (in case of acute crisis)

Symptoms are often chronic and/or intermittent. However, very severe acute episodes are possible. Also called "Addisonian crises," they can be life-threatening for the animal.

5. Diagnosis: how to be sure my dog has Addison's disease?

This disease is rare and manifests with general symptoms that can be found in many conditions. Its diagnosis must be made by a veterinarian; it is based on the observation of biological abnormalities.

 Blood tests may show an abnormal ionogram (particularly hyperkalemia or increased blood potassium levels) or hypoglycemia.

The reference test is hormonal: a product that stimulates the adrenal glands is injected into the animal, and their reaction is observed by measuring cortisol levels in the blood. Low blood cortisol before and after stimulation is a sign of hypocorticism.

6. Treatment: what is the treatment for this pathology? Is there a vaccine?

•       Emergency treatment

An Addisonian crisis is a true emergency that must be managed without delay. The dog must be hospitalized in intensive care to receive intravenous fluids to rehydrate it and correct hypoglycemia and ionic imbalances. Intravenous corticosteroid injections are also administered.

•       Long-term treatment

This involves supplementing the dog with gluco- and mineralocorticoids. For this, oral corticosteroids are generally administered daily, and desoxycortone pivalate is injected approximately once a month. It may be necessary to "tinker" a bit to find the adequate dose for the sick animal. Treatment adherence is crucial.

 Blood tests must be carried out regularly to detect under- or overdosing, or relapses. Medication must not be stopped at the risk of triggering a severe acute crisis.

•       Vaccination

Since hypocorticism is not an infectious disease, there is no vaccine against this condition. However, for an animal weakened by Addison's disease, classic vaccinations and antiparasitic treatments should not be neglected. Premium nutrition is also recommended.

7. Life expectancy: can a dog recover from Addison's disease?

There is no possible cure because, when the first signs appear, the adrenal gland cortices are already 90% destroyed. The prognosis is guarded in case of an Addisonian crisis. In the long term, the life expectancy of well-treated and well-monitored dogs is good. Addison's disease in dogs is rare but must be managed early and with strict follow-up.

Article written by Isabelle Vixège, DVM.

FAQ - Addison's Disease in Dogs

Is Addison's disease genetic in dogs?

Addison's disease in dogs, also known as hypoadrenocorticism, is not directly hereditary in the classic sense, but there is a genetic predisposition in certain breeds. For example, Poodles, Terriers, and Bearded Collies are more often affected. Although the exact genetic transmission is not fully elucidated, it is known that hereditary factors can play a role in the development of the disease. However, other environmental or immunological factors can also contribute to its onset.

How is Addison's disease treated in dogs?

Treatment for Addison's disease in dogs primarily consists of replacing the hormones that the adrenal glands no longer produce. This is done by administering a corticosteroid (such as prednisone) and a mineralocorticoid (such as fludrocortisone or DOCP). Treatment is usually lifelong, and dosage may require regular adjustments based on signs and blood test results. Careful management and regular veterinary follow-up are essential to ensure the stability and quality of life of an affected dog.

What are the first symptoms of Addison's disease in dogs?

The first symptoms of Addison's disease in dogs are often vague and non-specific, which can make diagnosis difficult. Initial signs include lethargy, loss of appetite, vomiting, weight loss, and general weakness. The dog may also experience diarrhea, tremors, or appear depressed. These symptoms can appear intermittently, and their severity can vary, often worsening during stressful situations. Without treatment, the disease can progress to an Addisonian crisis, a potentially fatal medical emergency.

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

The life expectancy of a dog with Addison's disease, when properly diagnosed and treated, can be quite normal. With adequate hormone replacement therapy and regular veterinary follow-up, most dogs can live long and healthy lives, comparable to that of a dog without the disease. However, it is essential to carefully monitor symptoms and manage dosage adjustments, especially during stressful situations, to prevent Addisonian crises which can be severe.