Cushing’s Disease

Has your pet recently been diagnosed with Cushing’s disease? Sometimes it can be difficult to process the information your veterinarian is telling you after they’ve given you the news about your beloved furry friend. To help you understand this condition better, please read on.

What is Cushing’s disease?

A pet with Cushing’s disease (also known as hyperadrenocorticism) has over-active adrenal glands. The adrenal glands are responsible for secreting hormones needed for various processes within the body. One particular hormone that is excreted is cortisol. A pet with Cushing’s disease has an adrenal gland that produces too much cortisol. Excessive amounts of cortisol can cause suppression of the immune system, damage other vital organs and impact metabolism. This increases the chances of infections and other diseases. Cushing’s disease is more common in dogs than cats and is generally identified in dogs over 6 years of age.


  • Hair loss
  • Bloated stomach (‘pot-belly’)
  • Behvioural changes
  • Thinning of skin
  • Loss of muscle mass
  • Increased drinking and urination
  • Increase appetite
  • Panting
  • Lack of energy
  • Weight gain

How is Cushing’s disease diagnosed?

The veterinarian may begin to suspect Cushing’s disease from a pet’s appearance, and based on information about behaviour at home given by their owners. Increased drinking, appetite and hair loss are common first signs that may prompt a pet owner to bring their pet in for a check up.

There are two blood tests that can detect Cushing’s disease. One is called an ACTH stimulation test and the other is called a low-dose dexamethasone suppression test. The most common test used is the low dose dexamethasone suppression test but your veterinarian will discuss the best test for your pet.


The treatment for Cushing’s disease fortunately is nothing other than medication. The medication is effective and with regular blood tests throughout the year your pet’s cortisol levels can be monitored to ensure they are always taking a suitable dose.

If you notice your pet has any of the symptoms mentioned it is worthwhile to have a general checkup, or make sure to mention these symptoms at their next appointment. The earlier the disease is identified the easier it can be to manage and your pet can maintain a good quality of life.

Addison’s Disease – Hypoadrenocorticism

What is it?

Hypoadrenocorticism occurs when there is a decreased production of hormones by the adrenal glands. The opposite condition is Cushing’s disease, where there is an over production of hormones. The adrenal glands are located above each kidney. The two main hormones excreted by the adrenal glands are glucocorticoids and mineralocorticoids.

Glucocorticoids are responsible for regulating sugar, fat and protein metabolism in the body as well as providing an anti-inflammatory response when the body is under stress. Mineralocorticoids such as aldosterone help maintain electrolyte balance in the body. Two important electrolytes are sodium and potassium.

What causes it?

The three most common causes of hypoadrenocorticism are immune-mediated destruction, tumours of the adrenal gland and iatrogenic (caused by medications).

Immune-mediated disease is when the body’s immune system becomes destructive and attacks the adrenal gland tissue causing a decrease in hormone production.

Cancerous tumours invade healthy tissue as they grow, leaving less functional adrenal tissue to produce hormones.

Iatrogenic Addison’s disease is caused by supplementing a patient with corticosteroid medication, then suddenly withdrawing it. Many pets with skin allergies are prescribed corticosteroid medication (e.g. prednisolone) to control their itch. The adrenal glands have relied on the supplementation for so long they forget how to produce hormones and this is why these medications are slowly reduced over time.

What are the symptoms?

Addison’s disease generally affects middle-aged dogs and is mostly seen in female dogs. Cats are rarely seen to develop Addison’s disease.

Symptoms include:

  • Dehydration
  • Low blood pressure
  • Lethargy
  • Weight loss
  • Low body temperature and heart rate
  • Diarrhoea and vomiting
  • Increased thirst


A blood test will assist the veterinarian with the suspicion of the disease. Tests include a full blood count and biochemistry. When Addison’s is present an electrolyte imbalance will be seen. Finally the veterinarian will perform an ACTH stimulation test to confirm the presence of the disease. This involves taking a blood test before and after an injection of Synacthen (a synthetic adrenal gland stimulating hormone). This tests how well the adrenal gland is functioning.


When Addison’s disease is confirmed the veterinarian will administer treatment to correct any dehydration and electrolyte imbalances. This can include putting the patient on a “drip” (intravenous fluid therapy ) and medicating them with both mineralocorticoids and glucocorticoids. Once stabilised (this may take several days in hospital), medication is used to supplement the patient with vital adrenal gland hormones for the rest of the pet’s life.

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