Cortisol plays an important role in the bodies of most animals, including aiding immune and metabolic systems and keeping inflammation in check. Disease that disrupts proper production and function can cause serious complications.
First, with this excerpt from our article about cortisol, let’s look at how the body creates cortisol:
The adrenal glands, located in front of the kidneys, produce most of a body’s cortisol supply. The hypothalamus and the pituitary gland can sense how much cortisol is in a body’s blood. When they determine a lack of sufficient cortisol, the pituitary gland produces adrenocorticotropic hormone (ACTH) and sends it into the bloodstream. The ACTH signals the adrenal glands to produce cortisol. The cortisol then makes its way throughout the body and carries out its essential tasks. (The Importance of Cortisol in Cats and Dogs, Sandiaanimalclinic.com)
This is an intricate system of creation, communication, and utilization.
The most common adrenal disorder is Cushing’s disease (hyperadrenocorticism), occurring when a body overproduces cortisol. This disorder is more likely to be diagnosed in middle-aged and senior dogs rather than youngsters and is rare in cats. There are a few causes of this disease and we approach each one with unique treatments.
Cushing’s disease can be caused by long term use of steroid medications, a tumor of the adrenal gland, or a tumor of the pituitary gland. Pituitary tumors are the most common cause of Cushing’s disease, accounting for the majority of cases, followed by adrenal tumors. Any of these tumors can be benign or malignant.
Increased appetite, water intake, and urination are the most common symptoms of this disease. Other symptoms can include muscle weakness, developing a pot belly, lethargy, hair loss (alopecia), and skin fragility and thinness.
Diagnosis can be tricky and involve physical examination, recognition of clinical signs, complete blood count, urinalysis, and hormone simulation and hormone suppression tests. Also, other diseases that can present with similar symptoms must be ruled out.
Two common tests are a low-dose dexamethasone suppression test (LDDST) and an ATCH stimulation response test. These measure the body’s reactions to cortisol in differing circumstances. Both tests can offer the possibility of the disease, and the LDDST can point to whether the form of disease is adrenal or pituitary. Because these tests are sensitive, diagnosis is often a multi-step process. Once the presence of disease and its form are confirmed, a treatment plan can be formulated.
Apart from surgical removal of benign tumors, treatment of Cushing’s disease is more about controlling rather than curing. Surgical removal of tumors, radiation, medication, treatment of concurrent disease, and comfort care are typical treatments, often used in various combinations, and depend on the cause of Cushing’s disease.
Cushing’s disease, the most common malady of the adrenal system, can be a complicated enemy to diagnose and treat. However, once diagnosed, and with proper treatment and diligent follow up, many dogs find relief and live healthy and happy lives.