Cushing's Disease in Dogs: Causes, Symptoms, and Treatment Options

This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed on August 23, 2024

If you have questions or concerns, call your vet, who is best equipped to ensure the health and well-being of your pet. This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. See additional information.

Recognizing the Signs of Cushing's Disease in Dogs

Is your dog slowing down, putting on weight, and sleeping more?

• If they are over a certain age, you might attribute these changes to the natural aging process.
• But what if a treatable condition mimicked old age and could help your dog regain their energy? You’d want to know about it, right?

Such a condition does exist — it's called Cushing’s disease. Cushing’s disease is a common hormonal disorder that affects middle-aged and older dogs. This condition is rare in cats.

Understanding Cushing's Disease in Dogs

The symptoms of Cushing's disease in dogs are caused by an excess of corticosteroids in the bloodstream, leading to: Increased thirst Thin skin A potbelly Other noticeable signs

Most cases of Cushing's disease result from overactivity in cortisol-producing glands, specifically the adrenal and pituitary glands. A smaller number of cases are caused by tumors in these glands.

Certain dog breeds are at a higher risk of developing Cushing’s disease, including: Beagles Boston Terriers Boxers Dachshunds Poodles

Key Symptoms of Cushing's Disease in Dogs

Many people mistakenly attribute the signs of Cushing’s disease to old age. Common symptoms include:

• Gradual slowing down, reduced energy, and increased sleep
• Weight gain
• A sagging stomach that takes on a potbellied appearance
• A dull and sparse coat
• Thin skin with blackheads
• Increased thirst, leading to higher water intake and possible lapses in toilet training

Another significant consequence of Cushing’s disease is the development of high blood pressure, which increases the risk of an unexpected vascular incident, such as a stroke. Experts believe that high blood pressure related to Cushing’s disease is a leading cause of sudden, unexplained death in older dogs.

This video shows "Peggy dog," a dog whose shaking is a result of Cushing's disease:

What Causes Cushing's Disease in Dogs?

Cushing’s disease (hyperadrenocorticism) is caused by an increase in the secretion of natural steroids, specifically cortisol, which stimulates the body to produce these steroids. While it is normal for the body to produce steroids during times of stress — as they are essential for coping with stress — too much cortisol can lead to adverse effects.

• Excess cortisol: A constant high level of cortisol leads to clinical signs such as increased thirst and a potbelly. This hormone imbalance can originate from the pituitary gland in the brain or the adrenal gland near the kidney.
• Gland overactivity: Around 85–90% of Cushing’s disease cases are due to overactivity of these glands, with the remaining cases caused by tumors.
• Medication-induced Cushing’s: Another form of Cushing’s, known as “iatrogenic” or “medication-induced,” can occur if a dog is given high doses of oral steroids for a prolonged period. The effect of the drug mimics the body’s natural steroid production, sometimes leading to clinical signs.

Your vet will discuss the risks of steroid medication with you if your dog requires high doses to treat another medical condition.

Diagnosing Cushing's Disease in Dogs

Your vet may suspect Cushing’s disease based on your dog’s medical history and specific changes observed in a routine blood panel. However, a definitive diagnosis is essential before beginning any treatment.

• Special Blood Tests: There are three types of "stimulation" blood tests available, each examining a different stage in the steroid production process. While these tests are highly effective, no single test is 100% foolproof, and false negatives or positives can occur.
• Confirming the Diagnosis: If your vet believes the test results do not accurately reflect the suspected condition, they may recommend a second type of test to explore another aspect of the steroid manufacturing process.
• Adrenal Tumor Detection: If the tests indicate the presence of an adrenal tumor, an ultrasound scan of the kidney and adrenal gland is recommended to check for signs of cancer.

For more information on what’s involved in a routine blood panel or to learn about adrenal tumors, check out these resources.

Case Study: Meg the Staffie

Meg was once a lively dog and a star at her local agility club. However, over several months, her enthusiasm for exercise dwindled. Instead of jumping hurdles, she became more inclined to sleep.

• Weight Gain: Meg started to put on weight, which her family didn't worry about initially, as she wasn't burning calories like she used to.
• Increased Thirst: Meg also became thirstier, but her family attributed this to her aging. However, their concern grew when Meg started having urinary accidents while on vacation. After returning home, they decided it was time for a checkup.

Classic Clinical Signs

During the checkup, Meg's problem list included: Lack of energy Weight gain around the tummy (a potbelly) Drinking more Needing to pee more often Panting Poor coat Muscle loss on her back legs

These symptoms raised my suspicion that Meg had Cushing’s disease.

Diagnosing Meg’s Condition

Reaching a diagnosis can be tricky. In Meg’s case, blood tests were conducted to check the health of her kidneys and other organs. While her organs were healthy, certain changes in the results hinted at Cushing’s disease.

• Blood Test: To confirm my suspicion, I performed a blood test that stimulates the body to produce steroids. The results pointed to an issue in the pituitary gland, leading to the decision to start treatment.

In some cases, the results are less definitive. Additional blood tests or an ultrasound scan of the abdomen to check for enlarged adrenal glands may be necessary. After diagnosing Meg, we checked her blood pressure, which was very high, a common consequence of Cushing’s disease. Meg was started on medication to address this issue.

If Meg’s story reminds you of your older dog who is slowing down, remember that a visit to your vet could be the first step toward helping your pet regain their vitality.

Treatment and Prevention of Cushing's Disease in Dogs

• Treatment: Most cases of Cushing’s disease respond to once-daily oral treatment with trilostane (Vetoryl). The signs of the disease reverse slowly, and the medication is needed for life. Cases that do not respond to treatment are more likely to involve a tumor. If a tumor is located in the adrenal gland, surgery may be curative, though it is a complex procedure best performed at a specialist facility.

Once the dog is stabilized on Vetoryl, blood pressure should be monitored. If it remains high despite treatment, anti-hypertensive medication is essential to reduce the risk of sudden blindness or stroke.

• Prevention: Unfortunately, there is no known method of preventing Cushing’s disease, except in cases induced by steroid medications (iatrogenic cases). In such cases, giving the steroid tablet on alternate days can reduce the body’s dependence on the steroid and lower the risk of developing Cushing’s disease.

Dietary Considerations for Dogs with Cushing’s Disease

When managing Cushing’s disease in dogs, diet plays a crucial role in maintaining their overall health and well-being. Dogs with Cushing’s disease may benefit from a diet that is:

• Low in fat: To help manage weight gain and reduce the risk of pancreatitis, which dogs with Cushing’s are more susceptible to.
• Moderate in protein: To support muscle mass and maintain energy levels, especially since muscle wasting can occur in affected dogs.
• Rich in antioxidants: Antioxidants can help combat oxidative stress and support the immune system, which is often compromised in dogs with Cushing’s.
• Controlled in sodium: Lower sodium levels can help manage high blood pressure, a common issue in dogs with Cushing’s disease.

Consulting with a veterinarian or a pet nutritionist can help tailor a diet plan that meets the specific needs of a dog with Cushing’s disease, ensuring they receive the appropriate nutrients while managing symptoms effectively.

Long-Term Outlook for Dogs with Cushing’s Disease

The long-term outlook for dogs with Cushing’s disease largely depends on the timely diagnosis and proper management of the condition. With effective treatment, many dogs can live a good quality of life for years. Key factors influencing the prognosis include:

• Response to treatment: Most dogs respond well to medication like trilostane, which helps control symptoms. However, regular monitoring and adjustments to the treatment plan may be necessary.
• Monitoring for complications: Regular check-ups are essential to monitor for complications such as high blood pressure, diabetes, or infections, which can arise as a result of Cushing’s disease.
• Quality of life: While Cushing’s disease is a lifelong condition, with proper management, dogs can enjoy a good quality of life. Owners should stay vigilant for any changes in behavior, appetite, or overall health, and consult with their vet to make any necessary adjustments to the treatment plan.

In summary, while Cushing’s disease requires ongoing care, the prognosis can be positive with diligent management and regular veterinary support.

Frequently Asked Questions (FAQ)

References

• Peterson. “Hyperadrenocorticism.” Current Veterinary Therapy. W.B. Saunders. 1986.
• Tilley & Smith. “Hyperadrenocorticism (Cushing’s Disease).” The Five-Minute Veterinary Consult. Williams & Wilkins.
• “Cushing's Disease in Dogs.” VCA Hospitals. https://vcahospitals.com/know-your-pet/cushings-disease-in-dogs
• “Treating Cushing's Disease in Dogs.” U.S. Food and Drug Administration (FDA). https://www.fda.gov/consumers/consumer-updates/treating-cushings-disease-dogs
• “Cushing's Disease in Dogs: Symptoms, Diagnosis, and Treatment.” PetMD. https://www.petmd.com/dog/conditions/endocrine/cushings-disease-in-dogs-symptoms-diagnosis