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Cushing’s Syndrome

Randy Walker DVM

About Cushing’s Syndrome...

Cushing's Syndrome is a hormonal disease in which the adrenal glands become overactive and secrete too much hormone. Cushing's Syndrome (also called hyperadrenocorticism) is a disease of humans and dogs and rarely of cats.

Briefly, Describe The Normal Adrenal Glands And How They Function.

The adrenal glands are two small, bean shaped glands located near each kidney. These glands normally secrete hormones which regulate the body's weight, mineral balance, coat, and skin health among other things.

What Are The Symptoms Of Cushing’s Syndrome?

The "classic" symptoms of Cushing's syndrome are excessive thirst (called polydypsia), excessive urination (called polyuria), increased appetite (called polyphagia), abdominal enlargement (bloated abdomen), muscle weakness, increased panting, lethargy, obesity, hair loss, skin infections, and hyperpigmentation (age spots). Not all patients with Cushing's will show all of these symptoms. Cushing's is often a slowly progressing disease and in many cases it will be suspected, tested for, and diagnosed before the signs become severe. Also, Cushing's disease can often be present along with and secondary to other diseases (such as diabetes) and in many cases we test for Cushing's when these other diseases are encountered.

What Causes Cushing’s?

Naturally occurring Cushing's (that not occurring from overuse of cortisone-type medications) is usually caused either by an overactive pituitary gland signaling the adrenal glands to work harder than they should or by a hormone secreting tumor of the adrenal gland. The cause of the overactive pituitary gland is usually unknown.

How is Cushing’s Diagnosed?

To test for Cushing's we first take a small blood sample to check the resting level of hormone from the adrenal glands. Then we give the patient a small injection of a hormone (usually either dexamethasone or ACTH) and take a couple more blood samples several hours apart. This tells us how the adrenal glands have responded to our injection. Simply put, if the patient's system responds one way then they have Cushing's but if the system responds the other way they do not have Cushing's

How is Cushing’s Treated?

In uncomplicated cases Cushing's is treated by giving a tablet medication which suppresses the activity of the adrenal glands. We usually start with daily doses of the medication for a few days then shift to once every 5-10 days for maintenance.

What Can Happen If Cushing’s Is Left Untreated?

If Cushing's is left untreated the clinical symptoms listed above will become more severe. Untreated Cushing's patients have clinical signs similar to patients who have been on prolonged, high doses of cortisone-type medications for long periods of time. In addition to the initial clinical signs listed above (excessive water consumption and appetite, bloating, excessive urination, poor coat with hair loss, skin pigmentation, etc), if it's left untreated, Cushing's can eventually lead to diabetes, liver failure, kidney failure, hypothyroidism, chronic infections of the skin, ears, gums, eyes, or bladder, and obesity (which in turn adds to the tendency for heart disease, joint problems, and cancers). The life expectancy for the untreated Cushing's syndrome patient is greatly decreased.

What Is The Prognosis For Cushing’s Syndrome?

If treated properly, most Cushing's patients do well on a long term basis. In fact, some individuals are able to eventually go off medication for extended periods of time and sometimes permanently.

Briefly, Describe The Usual Maintenance Program For Cushing’s Syndrome.

After Cushing's is diagnosed, the patient is placed on medication to suppress the activity of the adrenal gland. This medication is usually continued once daily for several days, then shifted to once every 5-10 days. Another blood test is performed about one month after beginning the medication and the dosage of medication is adjusted on the basis of this test. After the dosage has been fine tuned, the patient is then tested every 6 months and the medication adjusted accordingly. As noted before, some patients can eventually be weaned off the medication altogether.

- Randy Walker DVM
Sun Lakes Animal Clinic
May 14,2004

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