Addison’s Disease in Dogs
Addison’s disease, also known as hypoadrenocorticism, is caused by the adrenal glands failing to produce enough essential hormones, particularly cortisol and, in many cases, aldosterone.
The adrenal glands are small glands located near the kidneys. The hormones they produce help the body respond to stress and regulate important functions, including fluid balance, blood pressure and electrolyte levels.
Addison’s disease is much less common than Cushing’s disease, which is caused by excessive levels of cortisol. Addison’s disease is uncommon in dogs and rare in cats.
Which dogs are affected?
Addison’s disease can affect any dog, although it is seen more frequently in young to middle-aged dogs and is more common in females. Certain breeds may also have an increased risk.
Symptoms of Addison’s disease
The symptoms can be vague and may come and go, which means Addison’s disease can be mistaken for several other conditions.
Possible symptoms include:
- Weakness or unusual tiredness
- Loss of appetite
- Weight loss
- Vomiting or diarrhoea
- Dehydration
- Shaking or trembling
- Increased thirst and urination
- Collapse
What a dog finds stressful will depend on its individual temperament. Changes in routine, boarding, travelling, surgery, illness or having visitors may cause symptoms to appear or worsen.
Addisonian crisis
In some dogs, the first obvious sign of Addison’s disease is a sudden and potentially life-threatening deterioration known as an Addisonian crisis.
How is Addison’s disease diagnosed?
Your veterinary surgeon will consider the dog’s symptoms, medical history and any medications it is receiving. Initial investigations may include blood tests, electrolyte measurements and a urine test.
Some dogs have low sodium and high potassium levels, although dogs with atypical Addison’s disease may not show these electrolyte changes. Low blood sugar, dehydration and changes that resemble kidney disease may also be found.
The main test used to confirm Addison’s disease is an ACTH stimulation test. This measures the level of cortisol before and after an injection of synthetic ACTH. A dog with Addison’s disease will show little or no increase in cortisol.
Treatment
A dog experiencing an Addisonian crisis will require emergency veterinary treatment. This usually includes intravenous fluids, replacement steroids and careful monitoring of blood pressure and electrolyte levels.
Once the dog is stable, lifelong medication is normally required to replace the missing hormones. Depending on the type of Addison’s disease and the dog’s individual needs, treatment may include:
- Regular injections to replace aldosterone
- Daily medication to replace cortisol
- Regular blood tests and veterinary check-ups
- Temporary increases in steroid medication during illness or periods of stress, as directed by the vet
Medication requirements vary between dogs and may need to be adjusted according to test results and the dog’s response to treatment. Medication must not be changed or stopped without veterinary advice.
Addison’s disease caused by medication
Long-term treatment with corticosteroid medication can suppress the adrenal glands’ normal production of cortisol. If this medication is stopped suddenly, the dog may develop symptoms similar to Addison’s disease.
Corticosteroid medication should therefore only be reduced or stopped according to a veterinary surgeon’s instructions. Addison’s disease can also occasionally occur following treatment for Cushing’s disease. This is known as iatrogenic Addison’s disease.
Outlook
With appropriate lifelong treatment, regular monitoring and prompt veterinary attention when necessary, most dogs with Addison’s disease can enjoy a good quality of life.