Cushing’s disease is a complex condition that affects approximately 100,000 dogs in the United States each year.¹ It’s a chronic condition that results from the overproduction of cortisol—a hormone vital for managing stress, metabolism, and immune function. When cortisol levels are too high, it can cause a wide range of health problems.

If your dog has been diagnosed with Cushing’s, understanding the type, clinical signs, and treatment options is key to managing their condition and ensuring a good quality of life.

What Is Cushing’s Disease?

Cushing’s disease, also known as hyperadrenocorticism, occurs when a dog’s adrenal glands, located near their kidneys, overproduce cortisol. Cortisol is crucial for regulating immune functions, metabolism, and stress response. Changes in cortisol levels can causes illness and can be potentially life-threatening if left untreated in dogs.

Typically, Cushing’s is a lifelong condition that requires medication and routine monitoring. Any underlying medical conditions caused by the disease must also be treated and managed.

There are three types of Cushing’s disease in dogs, called pituitary-dependent, adrenal-dependent, and iatrogenic Cushing’s disease.

Pituitary-Dependent Cushing’s Disease 

Pituitary-dependent Cushing’s is the most common form of Cushing’s, accounting for 80-85% of cases.² It’s typically caused by a small, non-cancerous tumor in the pituitary gland, near the brain, which causes an overproduction of adrenocorticotropic hormone (ACTH), stimulating the adrenal glands to produce an excess of cortisol.

A tumor that is small and benign is generally easier to treat than a larger tumor, which may cause neurological signs that make the treatment outcome less favorable.

Adrenal-Dependent Cushing’s Disease 

This type of Cushing’s occurs when a tumor grows in one or both adrenal glands, causing excessive production of cortisol.

About 50% of adrenal-dependent Cushing’s cases are due to benign tumors, and 50% are malignant.² In 14% to 50% of cases, there is a possibility that a malignant tumor may spread to other organs.²

Iatrogenic Cushing’s Disease 

This type of Cushing’s disease is unrelated to tumor growth. It occurs when oral or injected steroids are used chronically or given at high doses. This may occur when treating conditions like arthritis, allergies, cancer, or autoimmune diseases.

The steroid imitates the effects of cortisol, causing ACTH production to decrease and the adrenal glands to shrink. This results in clinical signs of Cushing’s.

What Are Clinical Signs of Cushing’s Disease in Dogs?

Cushing’s disease can be tricky to catch early since it’s a slow-developing disease. The signs are easily mistaken for other diseases or the effects of aging. They’re the same regardless of the type of Cushing’s.

Your dog may show the following signs of Cushing’s:

• Increased appetite
• Increased water consumption
• Increased urination
• Drowsiness or lack of activity
• Excessive panting
• Bloated or “pot-bellied” abdomen
• Thin skin
• Hair loss
• Poor coat health
• Hyperpigmentation (dark-colored-spots on the skin)
• Calcinosis cutis (hard, raised, white or pink nodules on the skin caused by calcium deposit buildup)
• Poor wound healing³

Dogs with Cushing’s may also come down with other medical conditions, such as:

• Blood clots
• Diabetes
• Gall bladder disease
• Neurological issues, such as circling or seizures
• Recurrent urinary tract infections
• Recurrent skin infections
• Sudden blindness²

One study highlights the connection between Cushing’s and diabetes in dogs, telling us that about 14% of dogs with Cushing’s also had diabetes mellitus,⁴ and 95% of dogs with diabetes had pituitary-dependent Cushing’s.⁴

How Is Cushing’s Disease Diagnosed in Dogs?

There are several steps involved in diagnosing Cushing’s disease. A thorough evaluation by your veterinarian is the first step. Unfortunately, no single diagnostic test is perfect for diagnosing Cushing’s. Your veterinarian is best suited to determine testing and may include:

• Comprehensive lab work to assess basic internal organ function, cell counts
• X-rays of the chest and abdomen to screen for cancer and rule out other issues
• Blood pressure to test that it is within normal parameters
• Urine culture and sensitivity to confirm if a urinary tract infection is present
• Abdominal ultrasound to evaluate the size and shape of the adrenal glands and other organs

If the initial diagnostic tests are suggestive of Cushing’s disease, your veterinarian may recommend adrenal gland functioning tests to confirm the diagnosis and help determine the type of Cushing’s disease present.

Treatment for Pituitary-Dependent Cushing’s Disease

This type of Cushing’s disease is not curable but can be well-controlled. You can maintain a good quality of life for your dog with proper treatment.

Medication typically decreases the amount of cortisol produced by the adrenal glands. With less cortisol in the body, the clinical signs of Cushing’s are lessened or alleviated.

Radiation therapy has successfully been used to treat larger pituitary tumors. However, it’s expensive and not readily available.

A surgery called hypophysectomy has also been successful. The procedure is complicated and should be performed by an experienced veterinary surgeon. It is important to discuss the potential complications and risks associated with the surgery with your veterinarian.

Treatment for Adrenal-Dependent Cushing’s Disease

Whenever possible, removal of the adrenal gland is the preferred treatment for adrenal-dependent Cushing’s. The surgery, called an adrenalectomy, is a complex surgery requiring a skilled veterinary surgeon. There is a potential for serious complications, and not all adrenal tumors can be removed surgically.

If a benign tumor is removed through this procedure, there’s a strong likelihood that your dog will regain full health.³ Medication may be used before surgery to help improve your dog’s general health and support a better outcome.

Malignant adrenal tumors can also be removed surgically and may help for some time, but the outcome may be less favorable than if the tumor was non-cancerous.³ Surgery alone may not cure malignant tumors. Chemotherapy, radiation therapy or other medications may be recommended.

If surgery isn’t an option, your veterinarian may recommend medication to reduce cortisol levels to improve your dog’s health and quality of life, but it does not cure their Cushing’s.

Treatment for Iatrogenic Cushing’s Disease

This form of Cushing’s disease is treated by slowly decreasing or stopping the medication that caused it. As the adrenal glands return to normal, your veterinarian may recommend medication to address any secondary problems your dog is experiencing from the condition.

The medical issues that were being treated by the steroids will likely recur once that medication is discontinued. Your veterinarian can consider alternative treatments for those issues.

The Outlook for Dogs with Cushing’s Disease

Dogs with pituitary-dependent Cushing’s can live two or more years depending on the severity and how well they respond to treatment.⁵

The outcome for adrenal-dependent Cushing’s depends on the tumor. Survival for dogs that have a malignant or large tumor surgically removed is about one and a half to four years.² For those treated medically, survival is about one year.² Removal of an entire benign tumor means a strong likelihood that your dog will regain full health. Often, it’s the secondary illnesses that lead to serious complications. Treatment frequently focuses more on improving quality of life.

For iatrogenic Cushing’s, the prognosis is generally good, though it depends on the impact of stopping the steroids on the original condition, whether other treatment is available, and the degree of damage to other organs.