Cushing’s disease in cats – it’s rare and more common in dogs

Cushing’s disease in cats or hyperadrenocorticism is an endocrine disorder (endocrine system secretes hormones) in which the adrenal glands persistently produce an excess of cortisol, creating an imbalance of hormones in the body. Cushing’s disease appears to be sex-linked in that 75% of cases occur in female cats. The disease can affect cats as young as four but it usually affects older cats.

Cushing's disease in cats
Cushing’s disease in cats. Photo: a generic photograph in the public domain of a cat at a vet surgery.
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Note: there is a specific form of Hyperadrenocorticism called Iatrogenic hyperadrenocorticism, which is caused by the administration of a high-dose of cortisol over a long period to treat allergies and inflammation caused by health conditions.

Hormones are molecules that act as signals from one type of cells to another. Most hormones reach their targets via the blood.

All multicellular organisms need “coordinating systems to regulate and integrate the function of differentiating cells.” Two mechanisms perform this function in higher animals: the nervous system and the endocrine system.

Hyperadrenocorticism occurs more commonly in the dog than in the cat. It is not very common in cats but is occurring more frequently.

It is difficult to diagnose Cushing’s disease in cats (see below)


Excess of cortisol in body. Hypercortisolism: Excessive levels of cortisol in the blood result in Cushing’s syndrome.

What is cortisol?

“Cortisol is a corticosteroid hormone produced by the adrenal cortex (in the adrenal gland). It is a vital hormone that is often referred to as the “stress hormone” as it is involved in the response to stress. It increases blood pressure and blood sugar levels and has an immunosuppressive action. In pharmacology, the synthetic form of cortisol is referred to as hydrocortisone, and is used to treat allergies and inflammation as well as cortisol production deficiencies. When first introduced as a treatment for rheumatoid arthritis, it was referred to as “Compound E.”

What causes the production of excess cortisol in the adrenal glands?

{Caveat: research indicates some slight variations in the cause and treatment from one article source to the next, but the central arguments are common to all research sources}

The adrenal gland malfunctions due (in almost all cases) to either a pituitary brain tumor (85% of cases) or an adrenal gland tumor.

The tumor in the pituitary gland results in the pituitary gland producing too much of the hormone (ACTH) that directs the adrenal glands so they produce too much cortisol.

The underlying cause of Cushing’s disease also results in other conditions.

What are the symptoms?

These include:

  • increased drinking and urinating
  • increased appetite
  • panting
  • pendulous appearance to abdomen – pot-bellied look
  • increased urinary and skin infections
  • decreased exercise tolerance
  • weight gain
  • hair loss
  • increased pigmentation of thinning skin (particularly on cats)
  • muscle weakness
  • failure to grow hair that has been shaved

Normally not all the symptoms are present. There might be 2-3 symptoms and sometimes none. The disease doesn’t cause obvious illness. Increased thirst may be the most obvious.

Cushing’s disease in cats in far less obvious. Often it goes undiagnosed. It is most commonly diagnosed in cats when it is difficult to work out a maintenance dosage of insulin for a cat with diabetes. This is a sign that Cushing’s disease is present as it has an adverse effect on the regulation of blood glucose in cats who have diabetes and Cushing’s disease.

What is the treatment?

See your veterinarian. There are drugs including a new drug that can help normalize the production of cortisol but it is rarely life threatening and a near normal life can be expected. Cortisone excess caused by tumor is treated by surgical removal of both adrenal glands and daily cortisone replacement tablets2. If it is iatrogenic hyperadrenocorticism, the veterinarian will reduce the medication causing the illness. Surgery to remove an adrenal gland may be advised. This is called an adrenalectomy. A hypophysectomy (removal of pituitary gland) may be advised but this is a risky procedure. Some radiation for pituitary tumors is used.


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1. Please note: sometimes the apostrophe has been left out of the word “Cushings” deliberately. Don’t ask me why!

2. Cat Owner’s Home Veterinary Handbook page 111.

4 thoughts on “Cushing’s disease in cats – it’s rare and more common in dogs”

  1. My cat is an old gal. She recently went from being skinny to having a pot belly and heavy breathing at times. No other symptoms. I was wondering why?


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