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Addison’s disease

Information for pet owners on Addison’s disease (hypoadrenocorticism).

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What is Addison’s disease?

Addison’s disease, also called hypoadrenocorticism, is a potentially life-threatening disease caused by inadequate levels of hormones produced by the adrenal glands (located in the abdomen near the kidneys).

The adrenal glands produce two types of hormones that are critical for life; glucocorticoids (cortisol) and mineralocorticoids (aldosterone). These hormones are vital for the normal function of almost every cell in the body, normal immune system function as well as the electrolyte (body’s ‘salts’) and water balance of the body.

What are the signs or symptoms of Addison’s disease?

Patients with Addison’s disease can have variable clinical signs. Some patients have only low grade, waxing and waning vomiting and diarrhoea, whereas some individuals present as emergencies when they experience what is known as an ‘Addisonian crisis’. This is when the deficiencies of these hormones cause severe electrolyte abnormalities (especially elevated level of potassium and reduction in sodium), marked dehydration and weakness. Blood glucose can also be low.

How is Addison’s disease treated?

An Addisonian crisis is treated with intravenous fluid therapy as well as replacement of these essential hormones. While in hospital, these hormones are both injected, especially if the patient is critically unwell. Once the patient is stable, then they are switched to oral prednisolone (glucocorticoid) and injectable Zycortal (desoxycorticosterone pivalate or DOCP, the mineralocorticoid). These medications are administered life-long and without them a life-threatening Addisonian crisis could develop. Some dogs are only lacking one of these hormones, usually cortisol, and thus only need glucocorticoid supplementation; we call this presentation ‘atypical Addison’s disease’.

The dose of both medications will likely need to be adjusted over time. Frequent blood tests are initially required to ensure the dose of medications is correct and the disease is well controlled. During periods of stress (for example, due to going to boarding kennels or because of other illness) the individual’s requirement for prednisolone is likely to be increased. Please contact us or your own vets for advice before such stressful situations and they can guide you about dose increases.

DOCP – this is an injection that is usually given every 28 days by your vets. The dose is adjusted based on serial blood tests performed at set time points:

  1. A blood test is performed 10 days after the injection as this is when the drug has its peak effect.
  2. A blood test will also be performed at 28 days and the next dose of DOCP is given.

Once the right dose of DOCP has been established, the frequency of blood monitoring will be reduced, unless there are clinical concerns. As explained above, DOCP is not required in cases of ‘atypical Addison’s disease.’

What kind of ‘clinical concerns’ may indicate the dose is too high?

If the dose of prednisolone is too high, you might observe the following clinical signs: increased thirst, urination and appetite, muscle loss and hair coat changes.

If the dose of DOCP is too high, you might observe increased thirst and urination, poor appetite and depression/ weakness. If any of these signs occur veterinary advice should be sought.

What is the prognosis for dogs with Addison’s disease?

The prognosis for dogs with Addison’s disease is usually very good if the disease is well managed and the patient monitored appropriately.

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