Cushing’s Disease in Dogs - Symptoms, Diagnosis and Treatment

Cushing’s disease in dogs is a common hormonal condition that develops when a dog’s body produces too much cortisol over a long period of time. Cortisol is often called the “stress hormone,” but it actually plays many important roles in the body, including regulating metabolism, controlling inflammation, supporting the immune system, and helping dogs respond to stress.

While cortisol is necessary for good health, excessive amounts can slowly damage nearly every system in a dog’s body. Over time, dogs with untreated Cushing’s disease can develop serious complications involving the kidneys, liver, skin, muscles, and cardiovascular system.

Also known as hyperadrenocorticism, Cushing’s disease most often affects middle-aged and senior dogs, although younger dogs can occasionally develop it as well. Because the symptoms usually appear gradually and may seem like normal signs of aging at first, the condition can sometimes go unnoticed for months before diagnosis.

What Causes Cushing’s Disease in Dogs?

There are several different causes of Cushing’s disease, and identifying the underlying cause helps determine the best treatment plan for your dog.

Pituitary-Dependent Cushing’s Disease

Pituitary-dependent Cushing’s disease is by far the most common form, accounting for roughly 80 to 85 percent of cases. This type occurs when a tiny tumor develops on the pituitary gland, a small gland located at the base of the brain.

The pituitary gland controls many hormone functions in the body, including signaling the adrenal glands to produce cortisol. When a tumor is present, the pituitary gland sends too many signals to the adrenal glands, causing excessive cortisol production.

Most pituitary tumors are benign. However, even benign tumors can still create significant hormonal imbalances and symptoms throughout the body.

Adrenal-Dependent Cushing’s Disease

Adrenal-dependent Cushing’s disease occurs when a tumor forms directly on one of the adrenal glands. The adrenal glands sit near the kidneys and are responsible for producing several important hormones, including cortisol.

This form accounts for approximately 15 to 20 percent of Cushing’s cases in dogs. Some adrenal tumors are benign, while others may be malignant and capable of spreading to other areas of the body.

Iatrogenic Cushing’s Disease

Iatrogenic Cushing’s disease develops as a side effect of long-term steroid medication use. Dogs that receive corticosteroids for chronic allergies, autoimmune diseases, inflammation, or other medical conditions may eventually develop symptoms that resemble naturally occurring Cushing’s disease.

This happens because steroid medications mimic cortisol in the body. When used for extended periods or at high doses, they can lead to excessive hormone levels.

Symptoms of Cushing’s Disease in Dogs

The symptoms of Cushing’s disease often develop slowly and gradually worsen over time. Many dog parents initially assume the changes are simply part of aging, which is one reasons the condition can sometimes go undiagnosed for quite a while.

One of the earliest and most noticeable signs is increased thirst and urination. Dogs with Cushing’s disease often drink significantly more water than usual and may need to go outside more frequently. Some dogs even begin having urinary accidents in the house despite being previously well-trained.

An increased appetite is also extremely common. Dogs with Cushing’s disease may seem constantly hungry and may beg for food more often than normal.

Many dogs develop a pot-bellied appearance due to muscle weakness and fat redistribution around the abdomen. Weight gain commonly occurs, especially around the stomach area, while the legs may actually appear thinner because of muscle loss.

Excessive panting is another frequent symptom. Dogs may pant heavily even when resting or when the weather is not particularly warm.

Changes involving the skin and coat are also very common. Some dogs experience thinning hair, patchy hair loss, or fur that grows back slowly after grooming. The skin may become thin, fragile, bruised easily, or appear darker than usual. Blackheads and hardened scaly patches can sometimes develop as well.

Other symptoms can include:

Lack of energy or fatigue

Muscle weakness

Difficulty exercising

Insomnia or restlessness

Recurring skin or urinary tract infections

Shrinking testicles in males

Because these symptoms overlap with several other medical conditions, proper veterinary testing is important so that you can get an accurate diagnosis.

How Veterinarians Diagnose Cushing’s Disease

Diagnosing Cushing’s disease can be somewhat challenging because no single test is perfect. Veterinarians typically combine physical examination findings, bloodwork, urine testing, and specialized hormone testing to reach a diagnosis.

Blood Tests and Urinalysis

Routine bloodwork and urine testing are usually the first step. Dogs with Cushing’s disease often have diluted urine and elevated liver enzyme levels.

While these tests alone cannot confirm Cushing’s disease, they can strongly suggest it and help rule out other illnesses that may cause similar symptoms.

ACTH Stimulation Test

The ACTH stimulation test evaluates how the adrenal glands respond to a hormone called ACTH, which normally triggers cortisol production.

During this test, blood is drawn before and after an ACTH injection. The results help veterinarians determine whether the adrenal glands are overproducing cortisol.

Low-Dose Dexamethasone Suppression (LDDS) Test

The low-dose dexamethasone suppression test is one of the most commonly used tests for diagnosing Cushing’s disease.

This test measures how your dog’s body responds to dexamethasone, a synthetic form of cortisol. Blood samples are collected before and after the injection to see whether cortisol production decreases normally.

Dogs with Cushing’s disease typically fail to suppress cortisol production properly.

Ultrasound Imaging

Veterinarians may also recommend an abdominal ultrasound. This imaging test helps evaluate the adrenal glands and check for tumors or enlargement.

Ultrasounds can also help identify complications or other conditions that may be contributing to your dog’s symptoms.

Treatment for Cushing’s Disease in Dogs

Treatment depends on the underlying cause of the disease, the severity of symptoms, and your dog’s overall health.

Managing Iatrogenic Cushing’s Disease

If steroid medications caused the condition, your veterinarian will usually gradually reduce the medication dosage over time. Steroids should never be stopped suddenly unless specifically directed by your vet because abrupt withdrawal can be dangerous.

Many dogs improve significantly once the medication is carefully tapered.

Monitoring Mild Cases

In some dogs with very mild symptoms, veterinarians may initially recommend close monitoring rather than immediate aggressive treatment.

Regular checkups and blood testing help track whether the condition is progressing or beginning to affect the dog’s quality of life.

Surgery for Adrenal Tumors

If an adrenal tumor is present and has not spread, surgical removal of the affected adrenal gland may potentially cure the disease.

However, adrenal surgery can be complex and carries some risks, especially in older dogs or dogs with additional health problems.

Trilostane for Pituitary-Dependent Cushing’s

The most commonly prescribed medication for pituitary-dependent Cushing’s disease is trilostane. This medication helps reduce cortisol production and can greatly improve symptoms in many dogs.

Dogs taking trilostane require lifelong monitoring and regular blood testing to ensure the medication dosage remains safe and effective.

While many dogs tolerate the medication well, possible side effects may include vomiting, diarrhea, lethargy, difficulty walking, and loss of appetite. Make sure you talk to your veterinarian if any concerning side effects develop.

Can Cushing’s Disease Be Prevented?

Unfortunately, Cushing’s disease cannot truly be prevented. However, avoiding unnecessary long-term steroid use whenever possible might help reduce the risk of iatrogenic Cushing’s disease.

The best thing dog parents can do is pay close attention to changes in their dog’s behavior, appetite, thirst, urination habits, skin, and energy level. Early diagnosis often helps improve treatment success and overall quality of life.

Living With a Dog That Has Cushing’s Disease

Although Cushing’s disease can sound overwhelming, many dogs continue to live happy, comfortable lives with proper treatment and monitoring.

Routine veterinary visits are extremely important because hormone levels can fluctuate over time and medication adjustments are often necessary.

At home, it’s important to monitor any changes in your dog’s appetite, thirst, urination, energy levels, and overall comfort. Keeping track of symptoms can help your veterinarian evaluate how well treatment is working.

Dogs with well-managed Cushing’s disease often enjoy many more years of good quality life. The key is early detection, consistent veterinary care, and staying alert for any worsening symptoms or medication side effect.