Cushing’s Disease in Dogs: Signs, Causes, and Treatment
Complete guide to recognizing, diagnosing, and managing Cushing's disease in your dog.
Understanding Cushing’s Disease in Dogs
Cushing’s disease, also known as hyperadrenocorticism, is an endocrine disorder that affects dogs when their adrenal glands produce excessive amounts of cortisol, a hormone essential for normal body functions. While cortisol is necessary for regulating metabolism, immune response, and stress management, too much of this hormone can damage vital organs and significantly impact your dog’s health and quality of life.
This condition typically develops in middle-aged to older dogs and can progress gradually, making early detection challenging for pet owners. Understanding the signs, causes, and treatment options is crucial for managing this chronic condition effectively and ensuring your dog remains comfortable and active.
What Causes Cushing’s Disease in Dogs?
Cushing’s disease in dogs can originate from different sources, leading to three main types of the condition:
Pituitary-Dependent Cushing’s Disease
This is the most common form, accounting for approximately 85% of Cushing’s cases in dogs. It occurs when a benign tumor develops in the pituitary gland, causing it to produce excessive amounts of adrenocorticotropic hormone (ACTH). This hormone signals the adrenal glands to produce abnormal levels of cortisol. While this type is not curable, it can be effectively managed with lifelong medication to maintain your dog’s quality of life.
Adrenal-Dependent Cushing’s Disease
This form develops when a tumor grows directly on one or both adrenal glands, causing them to overproduce cortisol. Adrenal tumors may be benign or malignant, and treatment options may include surgical removal depending on the tumor’s characteristics and your dog’s overall health status.
Iatrogenic Cushing’s Disease
This type results from prolonged administration of corticosteroid medications prescribed for other medical conditions such as allergies, autoimmune diseases, or inflammatory disorders. Unlike the other two forms, iatrogenic Cushing’s can potentially be reversed by gradually discontinuing steroid therapy, though this must be done carefully under veterinary supervision.
Recognizing the Signs of Cushing’s Disease
The symptoms of Cushing’s disease develop slowly and subtly, which is why many owners don’t notice them immediately. However, being familiar with these warning signs can help you seek early veterinary intervention:
Common Physical Symptoms
- Increased thirst (polydipsia) – Your dog may drink significantly more water than usual, appearing in 82 to 91 percent of cases
- Increased urination (polyuria) – Frequent bathroom trips, including accidents in the house, are often noticed alongside increased drinking
- Increased appetite (polyphagia) – Your dog may seem constantly hungry and beg for food more frequently
- Reduced activity and lethargy – Your dog may show less interest in exercise, walks, or play
- Excessive panting – Panting without exertion or heat exposure may increase noticeably
- Thin or fragile skin – The skin may become papery and vulnerable to injury
- Hair loss – Alopecia may occur symmetrically on the body, often starting on the trunk
- Abdominal enlargement – A characteristic “pot-bellied” appearance develops due to weakened abdominal muscles and fatty deposits
- Recurrent skin infections – Compromised immunity makes dogs susceptible to bacterial and fungal infections
Behavioral Changes
Beyond physical symptoms, dogs with Cushing’s disease may exhibit behavioral changes including increased irritability, restlessness, or alterations in their normal temperament. Some dogs become more anxious or show decreased interest in family activities.
Other Health Complications
Dogs with Cushing’s disease may experience increased susceptibility to urinary tract infections due to elevated urine production and compromised immune function. Additionally, poor wound healing and muscle wastage become more apparent as the condition progresses.
Diagnosis of Cushing’s Disease
Diagnosing Cushing’s disease requires a comprehensive evaluation combining clinical observation, medical history, and specialized diagnostic testing. There is no single definitive test, so veterinarians must integrate multiple assessment methods to arrive at an accurate diagnosis.
Physical Examination and History
Your veterinarian will begin with a thorough physical examination, assessing your dog’s overall health, body condition, coat quality, skin condition, and visible symptoms. They will also inquire about your dog’s complete medical history, including any medications your dog is currently taking, as some drugs can affect diagnostic results.
Blood Tests for Diagnosis
Two primary blood tests are used to diagnose Cushing’s disease:
Low-Dose Dexamethasone Suppression Test (LDDST) – This test measures cortisol levels before and after administering a low dose of dexamethasone, a synthetic corticosteroid. In healthy dogs, dexamethasone suppresses cortisol production, but in dogs with Cushing’s disease, cortisol levels remain elevated. The ACVIM consensus statement recommends more widespread use of the LDDST where strong suspicion of Cushing’s syndrome exists.
ACTH Stimulation Test – This test involves measuring cortisol levels before and after administering synthetic ACTH (adrenocorticotropic hormone). In dogs with Cushing’s disease, the adrenal glands overrespond to ACTH stimulation, producing abnormally high cortisol levels. This test can also help determine whether Cushing’s is pituitary-dependent or adrenal-dependent.
Imaging Studies
Ultrasound imaging of the abdomen may be performed to visualize the adrenal glands and pituitary region. Enlarged or abnormal-appearing adrenal glands may suggest adrenal-dependent Cushing’s disease. In some cases, advanced imaging such as CT or MRI scans may be recommended for further evaluation.
Treatment Options for Cushing’s Disease
While Cushing’s disease is typically a lifelong condition, it can usually be managed effectively with appropriate treatment. The specific treatment approach depends on the type of Cushing’s disease and your dog’s overall health status.
Medication Management
Medication is the most common treatment approach, particularly for pituitary-dependent Cushing’s disease:
Vetoryl (Trilostane) – This is the only FDA-approved drug for treating both pituitary- and adrenal-dependent Cushing’s in dogs. Trilostane works by inhibiting the enzyme responsible for cortisol production in the adrenal glands. It does not cure the disease but effectively manages symptoms and improves quality of life. Vetoryl should not be given to dogs with kidney or liver disease, those taking certain heart medications, or pregnant dogs.
Lysodren (Mitotane) – This medication, derived from the insecticide DDT, destroys cells in the adrenal glands that produce cortisol. It is also effective for managing Cushing’s disease and requires regular monitoring through ACTH stimulation tests to determine appropriate maintenance doses.
Surgical Treatment
Surgical options are available but less commonly performed:
- Adrenalectomy – Surgical removal of an affected adrenal gland may be considered for adrenal-dependent Cushing’s disease, depending on the tumor type and your dog’s overall health
- Pituitary surgery or radiation – These options exist for pituitary-dependent Cushing’s but are rarely performed due to potential complications and limited availability
Management of Iatrogenic Cushing’s
If your dog has developed Cushing’s disease from long-term steroid therapy, treatment involves gradually discontinuing the steroid medication under close veterinary supervision. The underlying condition being treated with steroids may recur, potentially requiring hormone replacement therapy or alternative treatment approaches.
Dietary and Lifestyle Management
Supporting medication with appropriate dietary and lifestyle modifications significantly enhances your dog’s comfort and overall well-being:
Dietary Recommendations
- Low-fat, high-quality protein diet – Helps manage weight gain and supports muscle health in dogs with weakened muscles
- Limited sodium intake – Reduces water retention and helps manage increased thirst and urination
- Prescription diet options – Your veterinarian may recommend specialized diets such as Royal Canin Gastrointestinal Adult Low Fat Diet or Hill’s Prescription Diet i/d
- Supplements – Omega-3 fatty acids and antioxidants may benefit skin and coat health
Lifestyle Modifications
Maintain a consistent exercise routine appropriate for your dog’s energy level and mobility. While dogs with Cushing’s typically show reduced activity, gentle regular exercise helps maintain muscle tone and weight management. Ensure your dog has frequent opportunities for bathroom breaks due to increased urination. Provide a comfortable, climate-controlled environment since excessive panting is common. Regular grooming and skin care routines help prevent secondary skin infections.
Monitoring and Long-Term Management
Successful management of Cushing’s disease requires ongoing veterinary monitoring and adjustment of treatment as needed. Regular blood tests and clinical evaluations are vital components of long-term care.
Monitoring Schedule
Frequent blood tests and veterinary checkups are typically required in the first few months after starting treatment to establish the correct medication dose. After initial stabilization, monitoring usually continues every few months, with frequency adjusted based on your dog’s response to treatment and medication tolerance. Your veterinarian will assess effectiveness through clinical signs, blood test results, and ACTH stimulation tests when appropriate.
Prognosis and Life Expectancy
The expected lifespan for a dog diagnosed with Cushing’s disease ranges from one to five years, depending on the selected treatment, how well your dog responds to therapy, and management of secondary health issues. Many dogs live comfortably with well-managed Cushing’s disease for several years with appropriate medical care and lifestyle adjustments.
Frequently Asked Questions About Cushing’s Disease
Q: Is Cushing’s disease curable in dogs?
A: Most cases of Cushing’s disease are not curable, particularly pituitary-dependent cases which account for 85% of diagnoses. However, the condition can be effectively managed with lifelong medication to maintain your dog’s quality of life. Adrenal-dependent Cushing’s may sometimes be treated surgically if an adrenal tumor is present and your dog is a suitable surgical candidate.
Q: How often does my dog need blood tests with Cushing’s disease?
A: During the initial treatment phase, frequent blood tests are necessary to establish the correct medication dose. After stabilization, most dogs require blood tests every few months. Your veterinarian will recommend a monitoring schedule based on your dog’s response to treatment and individual needs.
Q: Can Cushing’s disease be prevented?
A: Pituitary-dependent and adrenal-dependent Cushing’s disease cannot be prevented as they result from tumor development. However, iatrogenic Cushing’s disease can be prevented by using the lowest effective dose of corticosteroids for the shortest duration necessary when treating other conditions.
Q: What is the cost of treating Cushing’s disease in dogs?
A: Treatment costs vary depending on the medication chosen, frequency of monitoring tests, and your location. Trilostane (Vetoryl) is typically more affordable than mitotane (Lysodren). Monthly medication costs generally range from $30 to $200, plus veterinary visit and blood test expenses. Discuss cost considerations with your veterinarian to find the most suitable treatment option.
Q: Can my dog have a normal life with Cushing’s disease?
A: Yes, with appropriate medical management and lifestyle adjustments, many dogs with Cushing’s disease enjoy good quality of life. Consistent medication, regular veterinary monitoring, appropriate diet and exercise, and prompt attention to secondary issues help keep dogs comfortable and active.
References
- Treating Cushing’s Disease in Dogs — U.S. Food and Drug Administration. 2024. https://www.fda.gov/consumers/consumer-updates/treating-cushings-disease-dogs
- Cushing’s Disease in Dogs: Signs and Treatment — MedVet. https://www.medvet.com/cushings-disease-in-dogs/
- Cushing’s Disease in Dogs: Symptoms, Diagnosis, and Treatment — PetMD. https://www.petmd.com/dog/conditions/endocrine/cushings-disease-in-dogs-symptoms-diagnosis
- Diagnosing and Managing Cushing’s Syndrome in Dogs — Veterinary Practice. https://www.veterinary-practice.com/article/cushings-syndrome-in-dogs
- Cushing’s Disease in Dogs — VCA Animal Hospitals. https://vcahospitals.com/know-your-pet/cushings-disease-in-dogs
- Canine Cushing’s Syndrome: A Comprehensive Guide and the Role of Acupressure — Poll to Pastern. https://www.polltopastern.com/post/canine-cushing-s-syndrome-a-comprehensive-guide-and-the-role-of-acupressure
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