In Addison’s disease, the body’s production of so-called corticosteroids is reduced. Addison’s disease is less common in cats than in dogs.
Many functions in the body are dependent on steroids. The adrenal glands are organs that produce both mineral corticosteroids and glucocorticosteroids (including cortisol = the body’s equivalent of cortisone). For various reasons, this production can be affected or prevented and the cat can get various symptoms.
The most common type of Addison’s disease is immunocompromised. The immune system begins to attack its own tissue (in this case the adrenal cortex) which is destroyed. The production of steroids then decreases and eventually disappears completely. Other causes that can destroy the adrenal cortex and thus steroid production are tumors and bleeding. The cause of the problem can also be found outside the adrenal glands. An example of this is when the signal from the brain that controls hormone production in the adrenal glands is weak or absent.
Animals with Addison’s disease may show fairly non-specific symptoms such as lethargy, weakness, vomiting and diarrhea. They may also have poor appetite, increased thirst, lose weight and have poor blood counts.
There is also a more acute form of the disease, the so-called Addison crisis. The cat then ends up in a life-threatening condition with symptoms such as low blood pressure, shock, severe dehydration, disturbances in the heart rhythm, abdominal pain, elevated kidney values.
A cat with an acute Addison crisis should be treated as soon as possible as the condition can be life-threatening.
In cats with the more “vague” and nonspecific symptoms, there is a suspicion of Addison’s disease along with other, more common causes of illness, including as part of a larger investigation. Diseases that may be similar to Addison’s disease in some respects are kidney failure, gastrointestinal diseases, inflamed pancreas and liver disease.
Blood samples are taken to examine for possible electrolyte disturbances, elevated kidney values and the number of red blood cells. The cat may also be low in its blood sugar. A specific test to diagnose Addison is a so-called ACTH stimulation. ACTH is the hormone that sends the signal from the pituitary gland to the adrenal glands to produce more steroids. If the adrenal tissue is destroyed, for example due to immune disease, we get a poor or no response at all to the ACTH stimulation.
The treatment in an acute crisis is mainly large amounts of fluid directly into the blood. In this way, both the severe dehydration and the electrolyte disturbances are corrected. Cortisone is also given at this stage. If you have a large influence on the pH value in the blood or severe electrolyte disturbances, you may have to go in more specifically and correct this.
The longer-term treatment is lifelong and consists of tablets containing both mineral and glucocorticosteroids. Cats treated for Addison can live a good life but may be slightly more sensitive to stressful situations. Cortisone can then be given extra for a temporary period. The cat should have recurring, frequent check-ups at the beginning of its treatment, but when everything has stabilized, a few times a year will suffice.