Cushing's Disease in Dogs: Symptoms, Diagnosis & Treatment

Cushing's disease is the common name for hyperadrenocorticism, a condition where the body is exposed to too much cortisol for too long. Cortisol is a normal hormone made by the adrenal glands, and it helps regulate metabolism, inflammation, blood pressure, and the stress response. When cortisol stays high, it affects nearly every organ system.

There are three forms of Cushing's in dogs. Pituitary-dependent Cushing's is the most common and happens when a small tumor in the pituitary gland tells both adrenal glands to make too much cortisol. Adrenal-dependent Cushing's happens when a tumor in one adrenal gland produces excess cortisol on its own. Iatrogenic Cushing's is caused by long-term steroid medication use, such as prednisone or dexamethasone.

This disease usually develops slowly, which is why many pet parents first think their dog is "getting older" rather than becoming ill. Increased thirst, more frequent urination, and a bigger appetite are often the earliest clues. Over time, dogs may also develop a pot belly, hair thinning, panting, muscle loss, and repeated infections.

The good news is that many dogs can do well for years with the right plan. The best approach depends on the type of Cushing's, your dog's symptoms, other health conditions, and what level of care fits your family and budget. Your vet can help you compare conservative, standard, and advanced options.

The most common cause is a pituitary tumor. In these dogs, the pituitary gland produces too much ACTH, a hormone that tells the adrenal glands to release cortisol. This form is called pituitary-dependent hyperadrenocorticism and makes up the majority of naturally occurring cases.

A smaller group of dogs have an adrenal tumor that produces cortisol directly. This is called adrenal-dependent hyperadrenocorticism. Some adrenal tumors are benign, while others are malignant and may invade nearby blood vessels or spread to other parts of the body. That is one reason abdominal imaging matters so much in the workup.

A third cause is iatrogenic Cushing's, which develops after prolonged use of steroid medications. These drugs can be very helpful and sometimes lifesaving, but long-term exposure can create the same body changes seen with naturally occurring Cushing's. If this is the concern, your vet may recommend a slow taper rather than abrupt discontinuation.

Cushing's is seen most often in middle-aged and senior dogs. Breeds commonly reported as overrepresented include Poodles, Dachshunds, Boston Terriers, Boxers, Beagles, and many terrier breeds. Breed risk does not mean a dog will develop the disease, but it can raise suspicion when the classic signs are present.

Diagnosing Cushing's is rarely a one-test process. Your vet usually starts with a history, physical exam, bloodwork, and urinalysis. Dogs with Cushing's often have patterns such as a high alkaline phosphatase, elevated cholesterol, dilute urine, or evidence of infection, but these findings do not confirm the disease by themselves.

The next step is usually an endocrine screening test. Common options include the low-dose dexamethasone suppression (LDDS) test, the ACTH stimulation test, and the urine cortisol:creatinine ratio. Each test has strengths and limitations. LDDS is commonly used to screen for naturally occurring Cushing's, ACTH stimulation is often used when iatrogenic disease is a concern and is also used for treatment monitoring, and the urine cortisol:creatinine ratio can be helpful as a rule-out test when collected in a low-stress home setting.

Once Cushing's is suspected or confirmed, your vet may recommend an abdominal ultrasound to look at the adrenal glands and search for other changes, such as liver enlargement or bladder stones. Ultrasound can help distinguish pituitary-dependent from adrenal-dependent disease, although some dogs still need additional testing. In more complex cases, referral imaging such as CT or MRI may be used for surgical planning or to assess a larger pituitary mass.

A practical US cost range for diagnosis in 2025-2026 is often $500-$1,500 for exam, lab work, endocrine testing, and ultrasound, though referral-level imaging can push the total higher. Because false positives and look-alike conditions can happen, it is reasonable to ask your vet what each test will add before moving forward.

Naturally occurring Cushing's usually cannot be prevented. Pituitary and adrenal tumors tend to develop spontaneously, and there is no proven diet, supplement, or screening program that stops them from forming.

What you can do is improve the odds of earlier detection. If your dog is middle-aged or older, pay attention to changes in thirst, urination, appetite, panting, coat quality, and body shape. These signs often creep in gradually. Bringing them up early gives your vet a better chance to sort out whether Cushing's, diabetes, kidney disease, or another condition is involved.

Iatrogenic Cushing's is the form that is most preventable. If your dog needs steroids for allergies, immune disease, or inflammation, your vet will try to use the lowest effective dose for the shortest appropriate time, or discuss other options when possible. Never stop long-term steroids abruptly unless your vet specifically tells you to do so.

Routine senior wellness exams and lab work are also helpful. They do not prevent Cushing's, but they can catch patterns that justify earlier testing and treatment discussions. For many families, that leads to fewer surprises and a more manageable care plan.