One of my passions as a small animal veterinarian is to inform and educate pet parents on the overall health and wellness of their pets. I feel knowledge and understanding is crucial for pet parents to feel comfortable and at ease with all the medical decisions and choices they are making for their beloved pets.
Cushing’s disease in dogs is one of the many dog diseases all dog parents should be educated on. If you are a dog owner, you should know what Cushing’s disease is, the clinical signs to look for, and how to treat your dog if she is diagnosed.
What is Cushing’s Disease?
Cushing’s disease (otherwise known as hyperadrenocorticism) is an overproduction of cortisol in the body. The endocrine system is the system in the body that produces and regulates hormones, such as cortisol. Cortisol is important and critical for many functions in the body, such as responding to stress, modulating the immune system or helping to regulate sugar levels. When the body is producing too much cortisol, or when a dog is given too much corticosteroid medication (like steroids, prednisone or dexamethasone), this can lead to negative effects and damage to the body.
What Causes Cushing’s Disease?
The most common cause of naturally occurring Cushing’s in dogs is a benign (not cancerous) tumor of the pituitary gland (a gland that is in the brain). Cancerous tumors of the pituitary are far less common. These benign pituitary tumors, called pituitary dependent hyperadrenocorticism (PDH), account for 80-85 percent of the dogs diagnosed with Cushing’s disease.
The other 15-20 percent are caused from a tumor of the adrenal gland (a gland that is near the kidney). Adrenal tumors, called adrenal-dependent hyperadrenocorticism (ADH), can be benign or cancerous (the chances are equally probable).
Another cause of Cushing’s disease is from the administration of too much corticosteroid medication (such as prednisone, dexamethasone or Depo-Medrol). These type of drugs are commonly used to treat immune disorders, cancers, skin disease and/or allergies.
What Are the Symptoms of Cushing’s Disease in Dogs?
Middle-aged to older pets are most commonly diagnosed with Cushing’s disease. The most common symptoms of Cushing’s Disease in dogs are:
- Increased thirst and urination (polydipsia and polyuria, respectively)
- Increased hunger
- Increased panting
- Pot-bellied abdomen
- Loss of hair
- Recurrent infections of skin, ears, urinary tract, etc.
- Darkening of the skin
- Appearance of blackheads on the skin
- Thin skin
- Hard white scaly patches on the skin or elbows (associated with the disease calcinosis cutis)
- Lack of energy
- Inability to sleep (insomnia)
- Muscle weakness
- Fat pads on the neck and shoulders
- Neurologic abnormalities (circling, behavioral changes, seizures, etc.)
How Is Cushing’s Disease Diagnosed?
Your veterinarian will collect a detailed history of your pet’s health and symptoms and perform a thorough physical examination. Initially your veterinarian will want to run bloodwork (chemistry profile, complete blood cell count and a urinalysis).
If based upon initial assessment and screening blood tests your veterinarian suspects Cushing’s disease, more specific blood and urine diagnostic tests for Cushing’s disease will be performed. This includes testing your dog’s urine cortisol-to-creatinine ratios, a low dose dexamethasone suppression blood test, an ACTH stimulation blood test, high-dose dexamethasone suppression test and/or an abdominal ultrasound.
Your veterinarian will decide the best and most appropriate diagnostic testing and protocol for your pet.
How Do You Treat Cushing’s Disease in Dogs?
The type of Cushing’s disease your dog is diagnosed with will impact the treatment chosen. For Cushing’s disease caused by the administration of corticosteroid medications, we slowly wean your pet off these medications. It is important to note that these medications need to be weaned slowly. Your veterinarian will prescribe the proper weaning schedule. Removing these medications too quickly can result in life-threatening conditions.
Mild symptoms of Cushing’s disease in dogs may not need immediate treatment. Your veterinarian will recommend close monitoring of your pet. Treatment is generally started when your pet is exhibiting symptoms that can be dangerous.
For pituitary dependent hyperadrenocorticism—if your veterinarian recommends treatment—it will generally involve one of two drugs: mitotane (Lysodren) or trilostane (Vetoryl). These treatments are usually prescribed for life. Your veterinarian will have you closely monitor your pet for adverse reactions, such as lack of energy, weakness, lack of appetite, vomiting, diarrhea or sometimes difficulty walking. If any of these signs are noted, have your pet seen by your veterinarian immediately. Your veterinarian will monitor your pet for proper dosing of medications.
If your pet has been diagnosed with adrenal gland dependent hyperadrenocorticism, your veterinarian will recommend thorough scanning, such as a CT, MRI or ultrasound, to look for any evidence of metastasis (or spreading of the tumor to other areas of the body) before recommending treatment. If there is no evidence of metastasis, a medication called trilostane may be started followed with surgery to remove the tumor. If the adrenal tumor was benign, excision (surgical removal) is generally curative.
I hope this article helps pet parents to better understand Cushing’s in dogs and the treatments available. As always, the health and wellness of your pets are my top priorities. If you have any questions or concerns, you should visit or call your veterinarian. They are your best resource to ensure the health and well-being of your pets.