You Need to Know
Cushing's
Disease
Cushing's Disease Overview
Cushing's Disease (also called Cushing's Syndrome) is caused by prolonged excess cortisol, a stress hormone produced by the adrenal glands.
The adrenal glands are located next to the kidneys and produce hormones like cortisol. The release of cortisol is regulated by ACTH, a hormone from the pituitary gland in the brain. When cortisol levels are low, the pituitary releases ACTH to signal the adrenal glands to produce more cortisol.
There are five forms of Cushing's Syndrome (also called hypercortisolism), which affect both dogs and cats:
-
Pituitary-dependent hypercortisolism (85% of cases): The pituitary gland releases too much ACTH, overstimulating the adrenal glands to produce excess cortisol.
-
Adrenal-dependent hypercortisolism (14% of cases): A tumor in the adrenal glands produces extra cortisol.
-
Iatrogenic hypercortisolism (rare): Caused by excessive and often long-term use of corticosteroids (e.g., prednisone or dexamethasone).
-
Ectopic ACTH secretion: For example, from a neuroendocrine tumor in the pancreas.
-
Food-dependent hypercortisolism.
Cushing’s disease is common in middle-aged and older dogs but rare in cats.
Symptoms of Cushing's Disease
Cushing's disease typically has a slow and gradual onset, so the symptoms are often overlooked in the early stages.
The most common symptoms in dogs are:
-
Excessive drinking and urination
-
Increased appetite
-
Increase in abdominal size
-
Symmetrical hair loss on both sides of the body
-
Thin skin
-
Reduced muscle mass (due to muscle breakdown)
-
Reduced endurance
-
Facial paralysis
-
Diabetes (in 10% of cases)
-
Urinary tract infections (in 50% of cases)
The most common symptoms in cats resemble those of diabetes:
-
Excessive drinking and urination
-
Weight loss despite increased appetite
-
Symmetrical hair loss on both sides of the body
-
Skin infections (e.g., demodicosis)
-
Thin, fragile skin that tears easily
-
Drooping belly
-
Lethargy
In about 80% of cases, diabetes is also seen in cats with Cushing's disease. One of the most common reasons to suspect Cushing's disease in a cat is when the cat has very difficult-to-control diabetes, even with high doses of insulin.
Diagnosis
Blood tests can provide an initial indication.
The diagnosis can be confirmed through urine testing, measuring increased cortisol excretion. Since cortisol levels in urine can also rise due to stress, the urine should be collected in the morning, during the first walk with the dog, by the owner.
In cats, diagnosing Cushing's disease is more difficult due to their stress sensitivity.
Treatment Options
Wat zijn de behandelingsmogelijkheden?
De behandeling van het iatrogene type bestaat uit het langzaam afbouwen van de corticosteroïdentabletten. De tijd die nodig is voor het afbouwen hangt af van de dosering en de duur van de behandeling met corticosteroïden.
Medications
In some cases, medication may be prescribed to reduce cortisol production.
​
Surgical Options
-
Pituitary Tumor: Surgery (hypophysectomy) may be necessary if there is a pituitary tumor.
-
Adrenal Tumor: If an adrenal tumor is present, an adrenalectomy (removal of the tumor) may be required.
Both surgeries carry risks. If an adrenal tumor has spread to the adjacent blood vessel, the vena cava, or if the tumor has metastasized, surgery is no longer recommended.
In cats, brain surgery is not an option. For a pituitary tumor in cats, both adrenal glands are removed. However, cats with Cushing’s disease are very fragile surgical candidates, which makes the surgery riskier in cats than in dogs.
Prognosis
The symptoms generally worsen gradually.
The survival time depends on several factors, including:
-
The type of Cushing's disease
-
The location, size, and type of tumor
-
Additional diseases
-
The age of the animal
-
The treatment method
Prognosis by type:
-
The pituitary-dependent type has a good short-term prognosis. However, the long-term prognosis is less favorable, as pets with Cushing's disease are more susceptible to other diseases, such as diabetes, urinary tract infections, kidney diseases, high blood pressure, and pancreatitis.
-
The iatrogenic type has a good prognosis.