Back to Client Info Index

Cushing's Disease (hyperadrenocoticocism)

General Information

Cushing's disease is a disorder of the adrenal glands in which excessive adrenal hormones are produced. The cause of hyperadrenalism may be abnormal pituitary gland function, tumors of the adrenal gland, "cortisone" therapy or unexplained overactivity of the adrenal gland.

Hyperadrenalism is a slowly progressing disease, and the early signs are often not noticed. These include increased appetite, increased drinking and urination, reduced activity and enlargement of the abdomen. As the disease progresses, these signs intensify, and the pet may become fat, pant heavily and lose hair evenly over each side of the body. In some cases, hair loss may be the only apparent change.

Extensive laboratory tests and radiographs (x-rays) are needed to diagnose the condition, find its cause and plan treatment. Some animals repond to medical treatment alone, while others need both surgical and medical treatment. Unfortunately, some patients grow worse despite treatment.

Important Points in Treatment

1. Control, rather than cure, is the outcome of treatment in most cases of hyperadrenalism. Treatment must be carefully monitored, since the drugs used in therapy may cause underproduction of adrenal hormones and a shock-like state known as an Addisonian crisis.

2. Give all the medication as directed. Call the doctor if you cannot give the prescribed medication or if you see any unusual behavior or signs after giving the medication.

3. Diet: Follow the instructions checked.

____Feed the normal diet.

____A special diet is required. Feed as follows: ____________________________________________________


Special instructions: _________________________________________

Notify the Doctor if Any of the Following Occur:

* Your pet drinks excessively or cannot hold its urine.
* Your pet vomits or has diarrhea.
* Your pet becomes depressed or weak, or behaves oddly.
* Your pet's skin condition worsens or does not improve.
* Your pet's general health declines.

Understanding Your Pet's Medical Diagnosis

Hyperadrenocorticism is one of the most common hormonal (endocrine) disorders in dogs. It is rare in cats. Hyperadrenocorticism is a disorder caused by the harmful effects of high steroid (cortisol) concentrations on multiple organ systems. Cortisol (or hydrocortisone as it usually is referred to pharmaceutically) is a hormone secreted by the adrenal glands. It is produced specifically by the adrenal cortex that is the outer layer of the adrenal gland. The adrenal cortex comprises the larger part of the adrenal gland. Another name for hyperadrenocorticism is "Cushing's disease."

What causes hyperadrenocorticism?

Most cases of hyperadrenocorticism are caused by enlargement of the adrenal cortex. The enlargement may be caused by tumors of the adrenal gland or of the pituitary gland. The tumors can be benign or malignant (cancerous). The signs of hyperadrenocorticism also can be produced by the administration of corticosteroids (such as prednisone) to the animal for treatment of a variety of medical conditions. When this occurs, the disease is called "iatrogenic hyperadrenocorticism."

What are the signs of hyperadrenocorticism?

The signs of hyperadrenocorticism include numerous changes to the skin and body. A pet with hyperadrenocorticism may have only a few signs or numerous signs. The severity of signs varies, depending on the duration and degree of excessive cortisol in the body. Some animals are more sensitive to the effects of excessive cortisol than others; these animals may develop signs more quickly and may have more severe disease. The signs include:

How is hyperadrenocorticism diagnosed?

The veterinarian will obtain a good medical history and perform a physical examination to determine what clinical signs are present. Other diseases, such as diabetes mellitus or hypothyroidism, may have similar signs. The veterinarian will differentiate hyperadrenocorticism from these other diseases based on physical examination and diagnostic testing. A variety of blood tests, blood chemistries, and urinalysis may be done to evaluate the animal. Some highly specific tests (such as dexamethasone suppression test or adrenocorticotrophin [ACTH] stimulation test) may be performed to provide a definitive diagnosis and to determine whether an adrenal gland or pituitary tumor is present. Radiographs (X-rays) of the abdomen and chest may help detect primary tumors and metastasis (the spread of the cancer to other parts of the body). Other imaging techniques (such as ultrasound, computed tomography [CT] scans, or magnetic resonance imaging [MRI]) are often useful. The veterinarian also may take the pet's blood pressure, as high blood pressure is associated with this condition.

Pets with hyperadrenocorticism may have additional medical problems, such as diabetes mellitus or urinary tract infections. These problems may be identified at the same time or after the hyperadrenocorticism is diagnosed.

How is hyperadrenocorticism treated?

In most cases, hyperadrenocorticism is treated medically. The veterinarian will choose a medication to treat the hyperadrenocorticism based on the laboratory testing and the identification of additional problems, if present. The pet may need hospitalization during initial treatment if the clinical signs are severe, or it may be treated as an outpatient. Lifelong therapy with medication is required. Follow-up examinations and blood tests will be necessary to monitor the pet and to evaluate response to treatment. If the pet does not respond to treatment, surgery to remove the tumor may be considered, if the animal is a good surgical risk and the cancer has not spread. Radiation therapy or chemotherapy may be considered.

What is the prognosis for animals with hyperadrenocorticism?

The prognosis (outcome) for animals with hyperadrenocorticism is variable. Clinical signs generally resolve within several days to months of appropriate treatment. In most cases, animals with pituitary tumor-related hyperadrenocorticism have a good prognosis with appropriate treatment. If these pets survive more than six months after the disease is controlled, they tend to die of causes unrelated to their hyperadrenocorticism. Medications may control the disease for two-to-four years. Untreated hyperadrenocorticism is generally a progressive disorder with a poor prognosis. The outcome for animals with malignant adrenal gland tumors can be good, if the cancer is small and has not spread. Pets with large cancers or adrenal gland tumors with widespread metastases generally have a poor prognosis, but impressive responses to high doses of chemotherapy occasionally are seen.

The majority of the information in this page is has been taken from VetMedCenter.com. For further information about this useful source of informtion follow the link or look, on the internet, at www.vetmedcenter.com.