Cushing’s syndrome, also commonly called Cushing’s Disease, is a common disorder of the canine endocrine system. Dogs with Cushing’s syndrome produce an excessive amount of a hormone called cortisol. Normally, cortisol helps the body respond to stress. However, over production of cortisol can have harmful effects on your dog’s organs, diminishing health and vitality.
The vast majority of dogs develop Cushing’s syndrome due to a tumor of the pituitary gland (Pituitary Dependent Cushing’s). Most of the time, these tumors are small and benign, yet they produce a hormone that stimulates the adrenal glands to produce cortisol. Uncommonly, these tumors are very large and can result in neurological problems in your pet. A smaller percentage of dogs with Cushing’s syndrome have a tumor of the adrenal gland (Adrenal Dependent Cushing’s). These tumors can be benign or malignant and can occur in either one or both adrenal glands. These tumors cause Cushing’s syndrome by producing excess amounts of cortisol. Rarely, dogs have a condition called “Atypical Cushing’s” where other hormones besides cortisol are involved.
Clinical Signs of Cushing’s Syndrome
Clinical signs of Cushing’s syndrome can be subtle and mimic changes that occur with normal aging. Some of the signs to look for include: Increased urinations (polyuria), Increased drinking (polydipsia), Increased appetite (polyphagia), Panting, Potbelly appearance, Muscle loss and muscle
Weakness, Lethargy, Hair loss, and Skin changes (thinning, recurrent infections, change in color)
Diagnosing Cushing’s Syndrome in Dogs
Diagnosis of Cushing’s syndrome requires sophisticated tests including special blood and urine tests that may require you pet spend the day at your veterinarian’s clinic. Even with these tests, Cushing’s can be difficult to diagnose, especially in the early stages of the disease or if your dog has concurrent medical disorders. An ultrasound examination may also be recommended to aid in the diagnosis of Cushing’s syndrome and determine whether an adrenal gland tumor is present.
Is Treatment Critical with Cushing’s Syndrome?
Cushing’s syndrome, although not a disease that is immediately life threatening, greatly impacts the quality of life for your dog and can impact the family as well. Dogs with this disease are at a higher risk for developing the following health problems:
- Diabetes
- Blood clots – mainly involving the lungs, legs and brain
- Infections of the lungs, skin, bladder, and kidneys
- Inflammation of the pancreas (pancreatitis)
- High blood pressure (systemic hypertension)
- Kidney failure
How is Cushing’s Syndrome Treated?
The treatment options are different depending on whether your pet has Cushing’s due to a problem with the pituitary gland or adrenal gland.
PITUITARY DEPENDENT
Although this form of Cushing’s is not curable, it can be managed so that your dog’s quality of life will be improved for years to come. The sooner you begin treatment of Cushing’s syndrome, the sooner your dog will begin to feel better.
Most dogs with Cushing’s syndrome due to a tumor of the pituitary gland can be treated with medications. The two most commonly used medications are Vetoryl (trilostane) or Lysodren (mitotane). These medications are usually given lifelong. Uncommonly, a CT scan and radiation therapy are indicated if the pituitary tumor is large and causing neurologic signs.
ADRENAL DEPENDENT
Dogs with adrenal gland tumors usually require surgery, and sometimes medications as well. Surgery can be curable.
What Should we Expect after Treatment is Started?
Once a medication has been started, you should see improvements in many of your dog’s signs over the following few weeks. These medications are usually given lifelong. Over time, your dog may require medication or dosage adjustment. Therefore, regular monitoring by your veterinarian is required to make sure your dog’s medication is working and that the dosage is correct.
Most commonly a blood test called an “ACTH Stimulation Test” is performed to determine if you dog is receiving the best dosage of medication. An ACTH Stimulation Test is evaluated within 2 weeks of starting therapy and usually every few weeks until your dog is receiving the right amount of medication. Thereafter, an ACTH Stimulation Test is typically evaluated every 3-4 months.
Alert your veterinarian and discontinue medication if you see any of the clinical signs: Decreased drinking, lethargy or weakness, any changes in appetite including eating slower or not finishing a meal, vomiting or diarrhea, increased sleeping, decreased activity.
Unfortunately, the majority of the time this disease is not cured. Rather, it is managed so that your dog’s life is of good quality for years to come. The sooner you begin treatment of Cushing’s syndrome, the sooner your dog will begin to feel better. Although massage therapy can be safe for cancer patients, your pet’s oncologist should be consulted before initiating. Any direct pressure over a tumor usually is discouraged.
