Unmasking Cushing’s: Understanding The Condition And Its Diagnosis

January 30, 2025

Cushing’s syndrome, or hypercortisolism, is a condition caused by overproduction of cortisol — a hormone that regulates stress, metabolism, and immune response. While cortisol is vital for normal body function, too much can lead to serious health issues.

Two Texas A&M College of Veterinary Medicine & Biomedical Sciences clinicians — Dr. Andrew Bugbee, a clinical associate professor of internal medicine, and Dr. Daisuke Ito, an associate professor of neurology — provide insight into this condition and how veterinarians diagnose it in dogs and cats.

The Science Behind Cushing’s

Cushing’s syndrome is most commonly caused by a benign tumor on the pituitary gland — a small, pea-shaped structure located at the base of the brain. This form of the condition, known as pituitary-dependent hypercortisolism, accounts for 85% of cases.

Often called the “master gland,” the pituitary plays a central role in regulating the body’s hormone production by signaling other glands, including the adrenal glands, to release hormones. The adrenal glands, located next to the kidneys, are responsible for producing hormones that regulate metabolism, blood sugar, immune responses, and stress levels.

“The pituitary gland acts like the conductor of an orchestra, signaling the adrenal glands to release cortisol,” Bugbee said. “When a tumor develops on the pituitary, it sends too many signals to the adrenal glands, causing an overproduction of cortisol.”

Less commonly, Cushing’s results from a tumor on one of the adrenal glands themselves, known as adrenal-dependent hypercortisolism. In this case, the tumor causes the affected adrenal gland to produce excess cortisol independently of the pituitary gland’s control.

While larger dogs are more prone to adrenal-based Cushing’s, patients of any size can develop either form of this condition. Both result in similar symptoms but may require different treatment approaches.

Recognizing The Signs

Owners should be watchful for the following signs of Cushing’s in their pets:

• Increased thirst and appetite
• Increased urination frequency and volume
• Hair loss, often along the chest, flank, and tail
• Panting, even when at rest
• Thin legs with a distended abdomen
• Dark, discolored, or thinned skin on the abdomen
• Blackheads on their belly

“These symptoms arise because cortisol affects nearly every organ system in the body,” Bugbee said. “If left untreated, Cushing’s can lead to serious complications, such as recurrent skin or urinary tract infections, ligament injuries, high blood pressure, kidney disease, blood clots, or damage to vital organs.”

In some cases, large tumors in the pituitary gland can also lead to neurological symptoms.

“When a pituitary tumor grows large enough, it can press on the brain, leading to seizures, vision problems, or changes in behavior,” Ito said. “This compression can also affect the animal’s consciousness and ability to coordinate walking.”

With its wide-ranging symptoms and potential for severe complications, early recognition and intervention are key to managing Cushing’s syndrome and improving a pet’s quality of life.

How Veterinarians Confirm Cushing’s

Diagnosing Cushing’s requires a careful and methodical approach, as its symptoms often overlap with normal aging or other conditions. Veterinarians typically begin with routine lab work to evaluate the pet’s organ function and blood cell counts.

“Abnormalities such as diluted urine, protein in the urine, elevated liver enzymes, changes in white blood cells, or high fat levels in the blood can raise suspicion of Cushing’s syndrome,” Bugbee said.

If initial tests point to the possibility of Cushing’s, veterinarians proceed with more specialized tests to examine how the pet’s body is managing cortisol.

“These tests can yield false positive results, especially if the pet is sick or stressed for other reasons or the tests aren’t done correctly,” Bugbee said. “That’s why it’s important for veterinarians to carefully evaluate a pet’s symptoms and health history before deciding to run these tests.”

By identifying the condition early, veterinarians can provide targeted treatments, improving a pet’s quality of life and mitigating long-term complications.

Pet Talk is a service of the College of Veterinary Medicine & Biomedical Sciences, Texas A&M University. Stories can be viewed on the web at vetmed.tamu.edu/news/pet-talk. Suggestions for future topics may be directed to vmbs-editor@tamu.edu.

Print