Canine Addison’s disease causes aren’t exactly known but there are several suspects, including a faulty immune system, vaccinations, and tumors:
- Faulty Immune System. Many practitioners believe that most cases of primary canine Addison’s Disease are because of the immune system attacking the adrenal glands and destroying it. The reasons for why the immune system attacks the tissue are mostly unknown. However, the inherited immune disorder granulomatous disease can be a cause of Addisons.
- Genetics: According to this research article, Addison’s occurs between 1.5% and 9% of domestic dogs, depending on breed. Some breeds, like Bearded collies and Standard poodles, have a high susceptibility to canine Addison’s (you can find a full list in this article of breeds more likely to have Addison’s). The Canine Genetic Analysis Project (CGAP) at the University of California found that out of 1470 Bearded Collies tested in the program (as of 2005), 92 had Addison’s disease, suggesting a high heritability and the possibility of a single recessive gene responsible for Addison’s disease. The team is still gathering data (as of 2009) for many breeds.
- Cancer: Cancer of the pituitary gland, adrenal lymphoma, or cancer that has spread to the adrenal glands from somewhere else (i.e. the lung or non-Hodgkin’s lymphoma) can cause Addison’s disease.
- Drugs: Addison’s disease can occur because of drugs that block corticosteroid (one of the adrenal hormones) synthesis in the body. One such drug is Ketoconazole–used in dogs and cats to treat fungal infections. An overdose of mitotane (a drug used to treat cancer of the adrenal glands) can also cause Addison’s disease.
- Inflammation/trauma: any kind of damage to the adrenal gland can cause Addison’s disease. It could be from something as simple as an infection or something as major as a car accident.
- Vaccinations: Some schools of thought have suggested vaccinations may trigger canine Addison’s disease. You can read about vaccinations for Addison dogs here.
Secondary Addison’s disease
is caused by pituitary gland problems, and like primary Addison’s can be caused by many different factors including inflammation, trauma and tumors.