The Great Imitator, that is how Addison’s disease has been called. Addison’s disease, or hypoadrenocorticism, is a relatively rare condition in which the adrenal gland fails to produce adequate levels of hormones (glucocorticoids and mineralocorticoids). It has been called the great imitator since it can cause very vague and non specific signs that mimic several other conditions. The low hormone levels can lead to several problems including decreased appetite, vomiting, diarrhea, weakness, increased water intake and urinations, weight loss and lethargy. With full blown Addison’s disease (low glucocorticoid and mineralocorticoid levels) severe problems such as collapse, shock and severe dehydration can develop. The signs can developed acutely or slowly over time, and can wax and wane, which makes obtaining a diagnosis sometimes a challenge. In a case of full blown Addison’s disease, there are classic signs seen in the blood work, such as a high potassium and low sodium that help to raise a level of suspicion. These changes can be absent when only cortisol, the stress hormone, is deficient. In these cases, the blood work can be completely normal. Although Addison’s disease is seen more frequently in some breeds such as Standard poodle, Portuguese water dog, Nova Scotia duck tolling retriever and Bearded collies, in which it is inherited, it can affect any breed, including mixed breed dogs. More commonly it affects young to middle age females but males and dogs of other ages can also be affected. Obtaining a baseline cortisol level is a test frequently performed in dogs with non specific or vague signs when Addison’s disease is suspected. A level below 2.0 is considered suspicious, in which case a follow up test of adrenal gland function called ACTH stimulation test is performed. In this test, a blood sample is obtained after which an injection of cortrosyn, which is similar to the hormone produced by the body to stimulate the adrenal gland, is injected. Another blood sample is obtained one hour later. A diagnosis of Addison’s disease is made if there is not a significant increase in the cortisol level. Treatment involves supplementation with the hormones that are deficient. Prednisone at very low doses similar to the cortisol levels that the body should produce and mineralocorticoids in the form of either oral Florinef (fludrocortisone) or injectable Percorten (desoxycorticosterone pivalate) are administered. Periodic monitoring of the blood work is important to make sure the doses of the medications are adequate. The prognosis is excellent as dogs can live a normal life as long as the hormones are supplemented. This is the case with Hunter, a three year old male Vizsla, which was diagnosed with Addison’s disease recently. Before his diagnosis he had been very sick. By the time of evaluation he was emaciated and so weak that he was almost unable to walk. He is now a healthy, happy and active dog.
Posted on: Wed, 19 Mar 2014 19:27:59 +0000
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