Imbalance in cortisol hormone can lead to serious, life-threatening conditions, says Yung-Tsun Lo, DVM, PhD of Bioguard Corporation.
Cushing’s disease (also known as Cushing’s syndrome or hyperadrenocorticism) is a condition where a dog’s adrenal glands produce too much cortisol, a hormone that helps regulate many body functions. The adrenal glands, located near the kidneys, make several important hormones, with cortisol being one of the most well-known. Imbalances in cortisol—whether too much or too little—can lead to serious and sometimes life-threatening health issues.
When cortisol levels are too high, dogs may show signs like drinking and urinating more than usual, increased appetite, panting, hair loss, and a pot-bellied appearance. This condition is fairly common, especially inmiddle-aged to older dogs.
What Causes the Disease?
There are three main types:
Pituitary-dependent (80 – 85% of all cases): A small, benign tumor of the pituitary gland in the brain may secrete excessive amounts of adrenocorticotropic hormone (AC TH), which in turn over stimulates the adrenal glands, leading to increased cortisol production.
Adrenal-dependent: A tumor (benign or malignant) on one or both adrenal glands causes excessive cortisol production.
Iatrogenic: This condition arises from prolonged or excessive administration of oral or injectable corticosteroids. Although corticosteroids are often prescribed for good medical reasons, using them in excess can end up causing harm.
What are the Signs of Cushing’s Disease?
Behavior Changes
- Drinking and urinating more than usual
- (seen in most cases)
- Increased hunger
- Heavy or frequent panting
- Tiredness or low energy
Appearance Changes
- Round, swollen belly
- Hair loss on both sides of the body
- Thin or fragile skin
- Hard lumps under the skin (due to calcium buildup)
Related Health Issues
- Urinary tract infections
- Skin infections
- Neurologic symptoms like seizures or walking in circles
- Blood clots
- Sudden vision loss
- Gallbladder problems
- Diabetes
How is Cushing’s Disease Diagnosed?
Diagnosis usually involves a combination of:
Physical Examination
Your veterinarian will perform a thorough assessment of your dog’s overall health, paying close attention to signs commonly associated with Cushing’s disease, such as increased thirst, panting, abdominal distension and hair thinning.
Blood Tests
Routine blood work helps exclude other conditions and provides insight into hormone levels, particularly cortisol, which is often elevated in affected dogs.
Urine Tests
The urine cortisol-to-creatinine ratio is a useful screening tool. Elevated levels may suggest Cushing’s disease, though further testing is needed for confirmation.
Confirmatory Tests
Two specialized tests are commonly used to diagnose Cushing’s disease:
ACT H Stimulation Test: Evaluates the adrenal glands’ response to synthetic AC TH.
Low-Dose Dexamethasone Suppression Test (LDDST): Assesses how cortisol levels respond to a synthetic steroid, helping differentiate between pituitary and adrenal causes.
How is Cushing’s Disease Treated?
Treatment aims to manage the symptoms and improve the dog’s quality of life. Options include:
Medication
Drugs such as Trilostane (Vetoryl) or Mitotane are commonly prescribed to reduce excessive cortisol production by the adrenal glands. These medications help manage clinical signs and improve quality of life.
Surgical Removal
In select cases, surgical removal of adrenal tumors may be considered, particularly when the disease is adrenaldependent and the tumor is localized and operable.
Radiation Therapy
For dogs with pituitary-dependent Cushing’s disease, radiation therapy may be available at specialized referral centers to target pituitary tumors and reduce hormone production.
What is the Prognosis of Cushing’s Disease?
With proper diagnosis and treatment, many dogs with Cushing’s disease can live comfortable lives for several years. However, it’s important to remember that Cushing’s is a serious condition and early diagnosis and treatment are crucial for a positive outcome.
