Cushing’s Disease in Dogs

Cushing’s Disease or Cushing’s Syndrome is a condition where the dog’s adrenal glands are producing an overabundance of hormones, specifically cortisone. Veterinarians refer to this as hyperadrenocorticism.

There are three types of Cushing’s disease, and they usually affect middle age to older dogs. Every kind of Cushing’s Disease affects the endocrine system. Any breed of dog can get Cushing’s Disease, but according to the American Kennel Club the Poodle, Boxer, Dachshund, Boston Terrier and Beagle are some breeds to watch. Most patients are elderly dogs over eight years old.

What Does the Endocrine System Do?

The endocrine system is a group of glands in the body which produce and release different hormones. These hormones regulate various body functions. The pea-sized pituitary gland, which is at the base of the brain, communicates with the adrenal glands and tell them when to release certain hormones, such as cortisone or cortisol. The Pituitary gland produces a hormone called adrenocorticotropic (ACTH).

ACTH communicates with the adrenal gland. The adrenal glands are peanut sized and located next to the kidneys. They produce a number of substances that regulate functions in your dog. Adrenal glands produce cortisone, helping to regulate the immune system, blood pressure, and blood sugar levels as well as improving the body’s response to stress. It is also referred to as the “fight or flight” hormone. Cortisone is meant to be produced in small amounts when your pet produces too much cortisone, then other problems develop.

Symptoms of Cushing’s

One reason Cushing can be difficult to diagnose is that its symptoms are similar to other diseases. Many of the symptoms are common attributes in an aging animal, often going unnoticed by pet owners. The overproduction of cortisone causes the dog to have an increased appetite, excessive drinking, and frequent urination. Your dog may not be able to hold his or her bladder and have accidents.

Additionally, your dog may develop a poor coat and act lethargic or sleepy. Hair loss is common and fat forms around the abdominal organs. As the abdominal wall weakens, it causes stretching of the abdominal muscles, giving the dog a potbellied pig appearance. Dogs with Cushing’s often develop skin problems such as skin infections, dark coloring or pigmentation and the inability to heal from skin irritations.

Different Types of Cushing’s Disease

Benign or malignant (less common) tumors can form on the pituitary gland at the base of the brain. Pituitary gland tumors cause 85 – 90% of all Cushing’s Disease in dogs. The tumor can trigger the pituitary gland to produce excess ACTH. This, in turn, stimulates the adrenal glands to produce excess cortisone.

When there is a tumor on the adrenal gland, the prognosis is more severe. These tumors have a 50/50 % of being benign or malignant and are more common in larger breeds.

Cushing’s disease can also be caused by excessive use of steroids, such as prednisone and dexamethasone. This is referred to as iatrogenic Cushing’s syndrome. Steroids are often given for legitimate medical concerns such as immune disorders, certain cancers and to reduce inflammation. However, their prolonged use can in turn trigger Cushing’s disease.

Diagnosing Cushing’s Disease

Cushing’s Disease is not always easy to diagnose. Veterinarians use a couple of necessary tests to check for Cushing’s. A blood test and fecal test. A urine test examines the cortisol: creatinine ratio to see if they are elevated. The ACTH stimulation test looks at how well the adrenal gland is functioning. The vet takes a blood sample before your dog receives a shot of ACTH. A few hours later your dog gets another injection of ACTH to see how or if it the hormone effects them. A normal response will cause the cortisone level to rise a small amount. If the cortisone level starts high and climbs higher after the injections then that is a good indicator for Cushing’s.

Another test that your veterinarian may utilize is a low-dose dexamethasone suppression (LDDS) test. In this test, the dog receives a shot of the hormone dexamethasone. This hormone inhibits adrenal production. If the cortisone level doesn’t lower then your pet have a tumor that is interfering with normal hormone production.

Additionally, the vet may take an abdominal ultrasound which allows them to see the size and condition of the adrenal gland to ascertain how it is functioning. A CT or MRI may be taken to look for any metastatic spread of the disease.

Treatment Options

Treatment is determined by what type of Cushing’s syndrome your dog has and how severe the symptoms. If your pet is experiencing mild symptoms, then you and your vet may wish to monitor and begin treatment when the symptoms become more severe.

The most common form of Cushing’s Disease, pituitary-induced, is also the most complicated to treat. There are several drugs that your vet may prescribe. The most widely used drugs are trilostane (Vetoryl) and mitotane (Lysodren). These drugs suppress the production of cortisone but have potential side effects so your pet should be monitored closely while taking medication. Vetoryl (trilostane) has been found to be effective in pituitary- and adrenal-related Cushing’s in dogs. According to the FDA, the most common side effects are:

  • Poor or reduced appetite
  • Vomiting
  • Lack of energy
  • Diarrhea
  • Weakness

More serious side effects can occur, such as bloody diarrhea, collapse, and severe sodium/potassium imbalance. Lysodren is a drug most often used on humans for chemotherapy that is not used often.

Your vet will prescribe enough of the drug to reduce symptoms but hopefully not bring about side effects. These medications will need to be administered for the rest of the dog’s life and your pet will need regular veterinary checkups as well to monitor the cortisone levels.

If your dog has an adrenal tumor, then surgery is the most common option. This surgery is complicated and expensive. If the tumor is benign, then a dog often makes a full recovery. If the tumor is malignant, it may only buy your dog some time as while it grows back. Medication can be prescribed in lieu of surgery.

Treating Cushing’s disease that is caused by overuse of steroids is complicated. You and your vet will want to discuss the reason steroids were given in the first place and what would be the effects of withdrawing the steroid. Cortisone should be withdrawn slowly, and your dog should be monitored throughout the process.

Dealing With Cushing’s Disease At Home

Now that you have a diagnosis and a medical treatment plan you are probably wondering what you can do to help your pet be comfortable and have a quality life. Once medication begins, it takes a week to several months for symptoms to be reduced.

If your dog has had surgery to remove a glandular tumor, they need to be monitored for internal bleeding. The incision should be closely watched for signs of infection.

Cushing’s disease causes excessive thirst so make sure your dog has plenty of clean water available. Since they may have mobility issues, keeping several bowls of water in different rooms is a good idea. Your dog will also have an increased appetite.

With drinking more water, your dog is going to have more frequent urination. You may notice the urine is paler in color which is a result of consuming more water. Your dog may also have more accidents and leak urine while they are sleeping. Use puppy pee pads in your dogs sleeping area and inside areas to protect your floors. Remember this is an accident and a result of your dog’s illness. Do not discipline your dog but try to give more frequent outside breaks and acceptable pee areas inside.

You may notice that your dog’s body composition changes. One of the symptoms in Cushing’s Disease is abdominal belly fat and a pot-bellied pig appearance. This can also lead to stretched skin on the back and a bony spine appearance. Keep in mind that your dog still wants attention and affection from you. However, as their body composition changes, they may desire attention in a different way.

Life Expectancy

Dogs with the pituitary gland type of Cushing’s Disease are expected to live three years longer on average. Since Cushing’s often occurs in elderly dogs some dogs may simply die of old age and not necessarily the disease. This disease can be controlled with medication, but it is not curable. Treatment is expensive, and your dog will need a regular check-up every 3 – 6 months to monitor the condition.

If your dog has had a successful surgery to remove a tumor on the adrenal glands then they may make a full recovery from the disease. In some cases, the tumor may grow back.

About the Author

Ame Vanorio is a freelance writer who specializes in blogs and articles on pets, wildlife, and veterinary topics. She lives on her farm in Falmouth, Kentucky with 5 fabulous dogs and numerous other pets.

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