Hyperadrenocorticism is a term denoting excess production of certain hormones by the adrenal glands.  Cortisol (cortisone) is the hormone responsible for the bulk of the symptoms seen.  Excess cortisol can result in increased thirst, increased urination, panting, increased appetite, weight gain, lethargy, thinning of the hair coat, recurrent infections, a pot-bellied appearance, reproductive problems and increased bruisability.  Unchecked hyperadrenocorticism can produce diabetes mellitus, hypertension, clotting problems, joint and ligament weakness/rupture, and liver abnormalities.

The excess hormone production is the result of a tumor in the adrenal gland (a small gland next to the kidneys) in approximately15% of cases, or in the pituitary gland (a small area at the base of the brain) in around 85% of cases. Tumors in the adrenal gland are usually treated by surgical removal.  Tumors in the pituitary gland usually remain small and are treated with medication.  Some pituitary tumors can grow large and produce other neurologic signs.

The diagnosis of Cushing’s syndrome requires several steps.  The disease may be suggested by abnormalities in the CBC (blood cell count), urinalysis, liver enzymes, other biochemical changes, the physical exam and history.  The disease is then confirmed by specific cortisol assays, with pre- and post- samples.  Once it is confirmed that hyperadrenocorticism is present, it is recommended to try and distinguish if the problem is in the adrenal gland or the pituitary gland.  Further cortisol assays (pre and post), abdominal ultrasound, ACTH hormone levels, an MRI or some combination of these may be used for this purpose.  Once the type of disease is determined, appropriate therapy can begin.

For the pituitary form, several medications are available.  Lysodren or mitotane has been used historically.  More recently, many patients are now being treated with trilostane (vetoryl).  There are other treatments available and consultation can help determine the best option for your pet.  Some of these medications can be harmful if used incorrectly and their use must be carefully monitored.

The prognosis for the pituitary from with a small tumor is fairly good once stabilization and maintenance therapy is achieved.  The pituitary form with a large tumor can result in life threatening neurologic complications and the prognosis is poor.  The large tumor form is fairly uncommon.  The prognosis for the form with an adrenal tumor is dependent upon how early it is diagnosed.  If the tumor is localized to the adrenal gland and surgery goes well, there is a reasonable chance for good recovery.  If the adrenal tumor has metastasized (spread to other organs) or is very involved in the abdominal blood vessels, the prognosis for long term survival is poor.