Addison's Disease in Dogs

Addison's disease, also known as hypoadrenocorticism in dogs, is a condition in which the adrenal glands of a dog do not produce enough corticosteroid hormone. When the disease is correctly diagnosed and treated, dogs can live long and happy lives.

The adrenal glands are two small glands located right next to the kidneys. These glands are responsible for the production of corticosteroid hormone, known as the stress hormone. There are two different types of corticosteroids: glucocorticoids and mineralocorticoids. Glucocorticoids affect the metabolism of sugar, protein, and fat. These metabolites are stored for use in fight-or-flight situations. Mineralocorticoids, on the other hand, are used to control sodium and potassium.

When dogs are under stress, their adrenal glands release stress hormones. The release of these hormones causes many minor and major changes in the body. A dog's body's response to stress can be listed as:

• Furiously climbing stairs,
• Looking anxious,
• Interacting with other dogs,
• Becoming excited.

In dogs with Addison's disease, the adrenal glands cannot secrete enough hormones to maintain normal stress levels. Without corticosteroid hormones, responses to stressful situations intensify. Even a very small source of stress can lead to serious problems, and in severe cases, even death.

Symptoms of Addison's Disease in Dogs

Addison's disease is a condition that is difficult to diagnose based solely on symptoms. This disease is usually detected during annual routine checkups through blood tests and electrolyte imbalances. The presence of symptoms such as whining, fatigue, loss of appetite, vomiting, and diarrhea in the dog will increase the suspicion of Addison's disease.

In 30% of dogs with Addison's disease, diagnosis is only made after an Addisonian crisis. During an Addisonian crisis, a dog goes into shock if it cannot adequately respond to an external or internal stressor. During this time, potassium levels rise, causing the heart rhythm to become irregular and excessively slow. Addison's disease also leads to hypoglycemia. An Addisonian crisis occurs when the outer layer of the adrenal glands loses its function. This crisis and the resulting shock are fatal if not treated urgently and properly.

Causes of Addison's Disease in Dogs

There are two different types of hypoadrenocorticism: primary and secondary. Primary hypoadrenocorticism occurs when the dog's immune system attacks the adrenal glands, resulting in drug-induced necrosis of the adrenal glands. This can be seen with the use of drugs such as ketoconazole, trilostan, and lysodern.

Secondary hypoadrenocorticism occurs as a result of decreased production of releasing hormones in the brain. Secondary hypoadrenocorticism is seen as a result of inflammation, cancer, brain trauma, or congenital disorders. Addison's disease usually affects dogs between the ages of 3 and 6, but there is a risk of it occurring at any age. It is more common in female dogs. The dog breeds most commonly affected by Addison's disease are;

• West Highland White Terrier,
• Great Dane,
• Basset Hound,
• Portuguese Water Dog,
• Airedale Terrier,
• Poodle,
• Bearded Collie can be listed. However, Addison's disease can occur in all dogs.

How is Addison's Disease Diagnosed in Dogs?

Many procedures are required to diagnose Addison's disease in dogs. Some of the tests performed on the dog include a medical history, physical examination, complete blood count, and ACTH test. The complete blood count checks for elevated potassium and decreased sodium levels. In atypical Addison's disease, electrolyte changes are not visible in blood tests. In some cases, elevated kidney enzymes can be mistaken for kidney disease, but this is rare. The primary method used to diagnose Addison's disease is the ACTH test. In this test, blood is first drawn to determine the level of the base stress hormone. Then, ACTH, the hormone secreted by the brain to stimulate corticosteroid release during stress, is administered intravenously. A blood test is performed again after one hour to check the dog's response to ACTH. If the cortisol level is low or only slightly different, a diagnosis of Addison's disease is made.

The primary method used to diagnose Addison's disease is the ACTH test. In this test, blood is first drawn to determine the level of the base stress hormone. Then, the ACTH hormone, which the brain secretes to stimulate corticosteroid release during stress, is administered intravenously. A blood test is performed again after one hour to check the dog's response to ACTH. If the cortisol level is low or shows only a very small difference, Addison's disease is diagnosed.

During the diagnostic process, blood tests may be required to measure urinary cortisol-creatinine levels, endogenous plasma ACTH, and plasma renin levels. Dogs of Pacific Rim origin, such as Shiba Inu or Akita, have high potassium levels in their blood. Diagnosing Addison's disease in these breeds is somewhat more difficult.

Treatment Methods for Addison's Disease in Dogs

Treatment during an Addisonian crisis consists of intravenous fluid therapy and steroid injections. Treatment for irregular heart rhythm and hypoglycemia may also be applied. Most dogs respond quickly to treatment and recover successfully.

The most important part of Addison's disease treatment is mineralocorticoid therapy. This treatment is administered orally in tablet form or by injection every 25-30 days. Electrolyte control and ACTH testing are performed at different intervals after treatment. These checks are usually scheduled 10 days, 30 days, and 90 days after treatment. Mineralocorticoid medications are generally used after electrolyte levels have stabilized. Glucocorticoid levels can be increased if the dog is under extra stress. Increasing the steroid dose slightly, especially during veterinary visits, car journeys, and times when the dog will be left alone, significantly reduces the likelihood of fatigue, vomiting, diarrhea, and most importantly, the risk of Addisonian seizures. Addison's disease is not completely curable, and affected dogs need to take medication for life. Dogs diagnosed with Addison's disease can live happy and long lives with treatment.

If the dog is under extra stress, the glucocorticoid level can be increased. Increasing the steroid dose slightly, especially during veterinary visits, car journeys, and times when the dog will be left alone, significantly reduces the likelihood of fatigue, vomiting, diarrhea, and most importantly, the risk of Addisonian seizures.

Addison's disease is not completely curable, and affected dogs need lifelong medication. Dogs diagnosed with Addison's disease can live happy and long lives with treatment.