Introduction
Hypoadrenocorticism, more commonly called “Addison’s disease” in dogs, is a disorder of the endocrine system which results from insufficiency or inadequate activity of the adrenal cortex. Addison’s is treatable with an excellent prognosis if the condition is detected, treated and monitored early in its course. Unfortunately, diagnosis can be difficult because the clinical signs of Addison’s mimic those of other more common ailments, such as renal failure, liver disease and gastrointestinal disorders, and these signs can wax and wane over time. However, watchful dog-owners normally are able to spot the symptoms of Addison’s, even though they may not know what is causing them.
Predispositions
Addison’s disease is more common younger to middle-aged female dogs, although dogs of any age or gender can be affected. It is unclear whether there are breed predispositions to this disease, but some authorities suggest that Great Danes, West Highland White Terriers, Bearded Collies, Standard Poodles, Rottweilers, Basset Hounds, Labrador Retrievers and Portugese Water Dogs are at increased risk.
Clinical Signs
Owners of dogs with Addison’s usually report that their pets demonstrate signs that come and go over time and range from mild and intermittent to very severe. These include weakness, lethargy, anorexia/lack of appetite, vomiting, regurgitation, diarrhea (that may be bloody), weight loss, abdominal pain, drinking more water than normal (polydipsia), urinating more than normal (polyuria), shaking/trembling and possible collapse. Another possible sign is if a dog deviates from things it usually does. For instance, if a dog shies away from jumping on a couch or bed that normally is not a problem for them, the owner should take note. That’s because pain and muscle weakness can also be symptoms of this disease. Obviously, all of these signs are somewhat vague and commonly ascribed to many other, more common disorders.
If left untreated, or if diagnosis is delayed, Addison’s can become life-threatening, primarily due to elevated potassium levels (hyperkalemia) and low sodium levels (hyponatremia) which cause serious and acute dehydration, volume depletion and problems with the heart, and other organs. Called an “Addisonian crisis,” the symptoms in this situation are among the same as those described above; they are just much more severe in their presentation. If an Addisonian crisis is not treated immediately and aggressively, death can result.