What is Addison’s Disease?
The medical name for “Addison’s Disease” is “Hypoadrenocorticism” also known as “Adrenal Insufficiency”.
Addison’s Disease is caused by an underactive ‘insufficient’ adrenal gland. The adrenal gland is located just in front of the kidney. The centre of the gland is called the medulla and the outer area is called the cortex. While both areas produce hormones, Addison’s disease concerns the hormones produced by the cortex; these hormones are called corticosteroids.
Corticosteroids are the hormones that enable us to adapt physiologically to stress. The glucocorticoids act on the mechanics of sugar, fat, and protein metabolism. It is a mechanism that enables humans and animals to mobilize a lot of energy rapidly, in order to cope with threats to survival. This refers to the term “fight or flight” response?
Corticosteroid hormones are needed to adapt to stressful situations and without these hormones, even small stresses could lead to a major physiologic disaster; an ‘Addisonian Crisis”.
There are three forms of Addison’s disease: primary, secondary and atypical.
Primary disease is the complete destruction of the adrenal gland (usually immune mediated) that leads to a deficiency of both glucocorticoids and mineralocorticoids. In dogs with primary disease, a metabolic crisis can occur that requires immediate treatment. In severe acute cases, the dog may go into Hypovolemic Shock (commonly known as “Addisonian Crisis”).
Secondary disease is usually only a deficiency of glucocorticoids and is usually due to underlying pituitary disease.
Atypical disease refers to primary or secondary adrenal gland failure in dogs that do not exhibit the classic symptoms or electrolyte abnormalities usually seen in Addison’s disease. Atypical will usually continue to develop into primary Addison’s disease.
Addisons Disease is more commonly diagnosed in dogs, whilst it is very rare in cats.
What Are The Symptoms of Addisons Disease?
Addison’s disease is known as the great imitator, quite simply because it has so many unspecific and generalised symptoms that it is often misdiagnosed or overlooked as a number of other conditions.
At first signs are vague or non-descript with listlessness, possible vomiting and/or diarrhoea. These can be periodic and continue for weeks and even many months. Generally the pet is not behaving right but not in any overly obvious way. Ultimately, the disease untreated will result in an “Addisonian Crisis”, where the dog collapses in shock due to the inability to adapt to circulatory requirements in stress. Blood sugar can drop dangerously low while Potassium levels peak at such a rate it disrupts the hearts rhythm simply because there is not enough conserved sodium to exchange for potassium. Heart rate slows, arrhythmias result. Many pets may not survive this episode.
Approximately 90% of the adrenal cortex will be non-functional before clinical signs are observed.
Approximately 30% of dogs with Addison’s disease are diagnosed at the time of an “Addisonian Crisis”
How Is It Diagnosed?
Electrolyte levels are important and certainly one of the first tests most veterinarians will undertake in order to help determine further testing for Addison’s. It is not however a definitive test for Addisons (quite simply because only Primary Addison’s effects the electroylytes).
The only definitive test for Addison’s disease is ACTH test. This tests the functioning of the adrenal glands stress response by measuring the adrenal response to adrenocorticotropic hormone (ACTH). It stimulates the adrenal glands to release cortisol and Dehydroepiandrosterone.
How Is It Treated?
Treatment is immediate and aggressive as death can occur from cardiovascular collapse.
High rates of fluids are given to restore hydration and improve perfusion and blood pressure. The high potassium often resolves with fluid therapy. Often a dose of short active steroid (glucocorticoid component) is given along with an injection of Percorten-V™ (DOCP) this usually helps to correct electrolyte abnormalities. Ancillary treatments include medications to control vomiting as well; such as Pepcid (famotidine) and carafate to protect the Gastrointestinal tract.
Once your dog is through the initial crisis, he will continue on physiologic doses of steroid (usually prednisone) for life. The Percorten-V™ (DOCP) intramuscular injections are also continued, usually every 25-28 days for life. The injections can also be replaced with a daily oral medication called Florinef ™ (fludrocortisone acetate).
These dogs are usually prone to stress related illness during their lifetime due to the adrenal gland inability to cope. If your dog is to be boarded or has to undergo surgery you must speak to your veterinarian. Your veterinarian may need to adjust the medication to reduce stress in your dog.
So What Now?
Management is the key! Yes, your dog will need medications and monitoring for the rest of his life, however most dogs return to a relatively normal life just as before the diagnosis. Learning your dog’s triggers to stress will be your best weapon in controlling Addison’s disease so that your dog can live a long happy life together!
Read about Corey’s Journey with “Addison’s Disease”.
Corey was one of the official dogs monitored to trial Percorten-V™ to grant approval for use in Australia by The Australian Pesticides and Veterinary Medicines Authority (APVMA). Corey was diagnosed with Addisons Disease after an Addisonian Crisis in 2003. He was 9 years old. Corey crossed over to the Rainbow Bridge in 2012 at 18 years old.
Read More About Autoimmune Diseases
Author Bio: Nikki is pack leader at Pressplay Pets, a blog for the modern age pet parent interested in health & care, news, reviews & personal accounts of unconditional love & at times heartfelt pain of pet parenting. She is also proud mum to cute and cheeky Papillons ‘Amber’ and ‘Indy’ and one crazy Rainbow Lorikeet named ‘Ralph’! Follow my Facebook and Twitter.
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