Cushing’s disease – otherwise known as Cushing’s syndrome or hyperadrenocorticism – is considered to be the most common hormonal disorder in middle-aged and older dogs. This condition can abnormally affect many systems in the body and shorten the lifespan of afflicted dogs. Fortunately, there is treatment available, and by recognizing symptoms of Cushing’s disease in dogs early, you can get your pup the help they need.

An Overview of Cushing’s Disease

Cushing’s disease is a condition that causes the adrenal glands to secrete too much of a hormone called cortisol. Excessive secretion of cortisol is most commonly caused by a small, slow growing, typically benign tumor in the pituitary gland, or more rarely, by an often malignant tumor in an adrenal gland. 

The symptoms of Cushing’s disease in dogs can also be caused by excessive or long-term administration of corticosteroid drugs – typically prednisone, prednisolone, or triamcinolone.

Different types of Cushing’s disease are managed in different ways:

• Cushing’s disease that’s due to a tumor in the pituitary gland is managed with medication 
• Cushing’s disease that stems from a tumor in an adrenal gland is cured with surgery
• Cushing’s-like symptoms as a result of corticosteroid drugs resolve when the dog stops taking the drug(s)

Signs and Symptoms of Cushing’s Disease in Dogs

Cushing’s disease has typically very recognizable symptoms, and it tends to behave the same way in most dogs. How severe the signs are depends on how long the dog has been affected by Cushing’s disease and how much excess cortisol is circulating in their system. The earlier you catch this disease, the less wear and tear it has on your dog’s body, and the faster they can return to normal with appropriate treatment. 

To help you spot any signs and symptoms of cushing’s disease in your dog, we’ve broken them down into two categories.

Early Symptoms of Cushing’s Disease in Dogs

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Increased appetite. We know that in people, excessive cortisol levels stimulate their appetite and lead to weight gain. The same appears to be true for dogs. Since insulin in part controls hunger and satiety, the mechanisms that cause this may be related to insulin resistance due to persistently high blood sugar, which is a result of excessively high cortisol. In addition, fat hormones that control hunger are disrupted by cortisol.

Increased urination. Excessive cortisol inhibits ADH, a hormone secreted by the kidney to concentrate urine in order to conserve body water. Thus, dogs affected by Cushing’s disease typically pee more than they typically should.

Increased thirst. Because dogs with Cushing’s are peeing more than normal, they’re chronically dehydrated, which causes them to drink more than normal.

Behavioral changes. Cortisol also functions as a fight or flight hormone, telling the body when to sleep and when to wake up. Chronically elevated cortisol in dogs can cause anxiety, excessive licking of surfaces like the floor, irritability, pacing, and abnormal sleep patterns.

Increased panting. There are several reasons why Cushing’s causes panting in dogs. Dogs with Cushing’s have weakened respiratory muscles. Coupled with an enlarged liver that keeps the diaphragm from expanding properly and abnormal fat deposits in the chest, this results in difficulty breathing and increased panting. Additionally, increased anxiety can also cause panting.

Increased shedding and hair thinning. Excessive cortisol disrupts hair growth, which can lead to thinner hair and shedding. Anxiety can also cause increased shedding.

Symptoms of Advanced Cushing’s Disease in Dogs

Pot belly. Over time, cortisol weakens muscles, including abdominal muscles. This, plus an enlarged liver that is associated with Cushing’s, causes a pendulous abdomen.

Hair loss. Because cortisol disrupts hair growth, dogs start to develop bald patches and hair loss called flank alopecia, usually on both sides of their body.

Skin changes. Excessively elevated cortisol disrupts normal skin cell growth over time and can cause many skin changes, including increased pigmentation, thin skin, excessive bruising, testicular atrophy, blackheads, bacterial infections, hardening of the skin (calcinosis cutis), and slow wound healing.

Urinary tract infections. Because elevated cortisol negatively impacts the immune system, dogs are more susceptible to viral and bacterial infections that they would normally have fought off. The most common are skin and urinary tract infections.

Obesity. Because dogs with Cushing’s eat more, move less, and have altered metabolism, they tend to gain weight quickly.

Weakness. Over time, cortisol weakens muscles and causes them to shrink. Dogs with Cushing’s often have shaky back legs and decreased endurance.

Palsy. Excessive cortisol can also cause facial nerve damage, resulting in a droopy, lopsided appearance to your dog’s face. Additional signs associated with facial nerve palsy can include messy eating, dropping food, extreme drooling, inability to close an eyelid, and discharge from the affected eye.

High blood pressure. Metabolic, hormonal, and electrolyte imbalances in Cushing’s can lead to a dog having elevated blood pressure. This puts additional wear and tear on the cardiovascular system, liver, and kidneys, and can also predispose a dog to stroke, blood clots, and other issues. Additionally, high blood pressure may cause a dog to feel anxious.

What To Do if You Notice Signs of Cushing’s Disease in Dogs

If you notice these signs and symptoms, it is often not an emergency, but an urgency. It is best to call your veterinarian as soon as possible to set up a consultation and physical exam for your dog. 

Your veterinarian will first want to get a history from you (i.e. what you’ve noticed at home and how long it’s been going on). They’ll then conduct a full physical examination and run some baseline tests, including:

• Blood chemistry to check electrolytes, blood sugar, and internal organ function
• A complete blood count to check blood cells
• A urinalysis to check urinary health 

These tests do not specifically diagnose Cushing’s disease, but they can rule out other problems that can cause a lot of the same clinical signs, such as diabetes, kidney disease, and liver problems.

If your veterinarian suspects Cushing’s, they’ll typically want to run additional blood tests. The most common test is called an ACTH stimulation test, which examines how your dog’s hormones respond to an injection of a hormone called ACTH. It’s a very sensitive test for Cushing’s and only takes two hours to complete. Other recommended tests may include dexamethasone suppression tests, a urine cortisol:creatinine ratio test, or measuring your dog’s ACTH levels.

While all of these tests can determine whether your dog has Cushing’s, they cannot differentiate between pituitary and adrenal disease. To find out which form your pup has, your veterinarian may also recommend imaging with abdominal ultrasound. This will tell you specifically whether your dog needs medication for pituitary disease or surgery for adrenal disease.

Fortunately, Cushing’s disease is a common hormonal condition seen in dogs, and it responds very well to treatment. If you notice these symptoms in your dog, seek help as soon as you can to get them back on the road to recovery.