Addison’s Disease

Addison’s is a manageable disease and the vast majority of patients respond favourably to treatment.

Addison’s disease is a hormonal disorder caused by the deficient production of cortisol or aldosterone, or both. Both of these hormones are normally produced by the adrenal glands, which live near the kidneys. However, if the adrenals are diseased or damaged, normal levels of hormone are no longer produced. Also the pituitary gland, (which is another hormone producing gland near the brain) can influence the adrenals and if it isn’t functioning normally, this can also cause a decrease in the level of cortisol and aldosterone.

 There are 2 broad groups of causes of Addison’s disease:

  • Primary Addison’s: This is when the adrenal gland function is destroyed by the immune system of the animal, or when it is idiopathic (no known reason or cause). In rare cases, underlying cancer or certain drugs can also play a part. It is an uncommon to rare disease in dogs and extremely rare in cats. Certain breeds seem to be more prone to the disease such as Great Danes, Rottweilers, Poodles, West Highland White and Wheaten Terriers. The average age that dogs seem to be affected is 4 years old but can be as young as 1 year old, through to 12 years of age.
  • Secondary Addison’s: This occurs when a patient who has been on a corticosteroid drug (the most common variety of this drug group dispensed by vet clinics is called prednisolone) is suddenly withdrawn from treatment, without being slowly weaned off the medication. This happens because while the patient is on the medication, the body’s natural production of cortisol hormone will be suppressed, and when medication is abruptly stopped, the body does not have a chance to reestablish its natural levels. Low cortisol levels can be very low, resulting in similar symptoms as those seen in primary Addison’s.

The symptoms are variable and may be few in number in some patients or may be severe and life threatening in others (this is referred to as an Addisonian crisis). The following are listed from the more typical, down to the less common signs that patients with Addison’s disease may present with: 

      • Lethargy and weakness 
      • Loss of appetite 
      • Vomiting 
      • Diarrhoea 
      • Weight Loss 
      • Shaking 
      • Increased thirst and urination 
      • Collapse

If your pet develops any of these symptoms listed, your vet will usually start with a general blood screening test. In cases of Addison’s disease, it is common to see electrolyte disturbances on this screen (ie sodium levels are lower and potassium levels are higher than normal), and sometimes anemia (low red blood cell count) and liver enzyme elevations can also occur. Because these results are indicative of Addison’s disease but not diagnostic, a second test is usually run to confirm the disease.

This is called an ACTH stimulation test and involves taking a blood test, then injecting the patient with a hormone called ACTH, which is designed to stimulate the adrenals to produce cortisol. A second blood test is then taken 1 hour later to see how much the cortisol levels have increased in the blood stream. If they have not increased at all, it suggests that the adrenals are not working and the animal has Addison’s disease.

Animals with Addison’s disease need to be on lifelong hormone replacement and may need increased doses during periods of stress such as travel, hospitalisation and surgery.

The medication is called “Florinef” (active ingredient fludrocortisone acetate), which is given once or twice daily, and the medication may be supplemented with prednisolone.

Initially, weekly blood tests are performed until their hormones are stabilised, then a blood test monthly to check their electrolytes and kidney function for the first 3-6 months, then every 3-12 months.

As the owner of an Addison’s pet, it is important that you keep a close eye on their behaviour, condition, the amount of food and water they take in, and any side effects of the medication. Addison’s dogs also require regular monitoring with blood tests, as described above.

If your pet shows any signs which are unusual or are concerning to you, while on medication, please contact your vet clinic.

Medication for this condition is life long, and should never be stopped at any stage without veterinary advice.


Florinef is a life-long medication, and will need to be purchased regularly. You will find that our pricing for chronic medications is less than other veterinary clinics and is supported by our price match guarantee. For more information, please contact your vet.

Please call us on (08) 6166 6329 if you have any concerns about your pet or would like more information


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