Panting and a pot-belly in your dog: A guide to pituitary Cushing’s symptoms and treatment options

EndocrineDiseasesMeongsiljang Veterinary Advisory Board

Pituitary tumors are the most common cause of Cushing’s disease in dogs. We’ve outlined the diagnostic process, treatment options such as trilostane and radiation therapy, and key points for home care.

What are pituitary tumors and Cushing’s disease in dogs?

An illustration of a senior dog nestled in its owner's arms

Pituitary tumors in dogs are small, benign growths that develop in the pituitary gland, a hormone-regulating organ located at the base of the brain. These tumors cause Cushing’s disease by overproducing hormones that stimulate the adrenal glands. Early diagnosis is crucial. Since 8 to 9 out of 10 cases of Cushing’s disease stem from pituitary tumors, it’s important to perform hormone testing promptly if you notice signs such as increased thirst, frequent urination, or a distended abdomen. Fortunately, most of these tumors are very small, and dogs can typically maintain a good quality of life with medication alone.

Why does it happen? Understanding the pathogenesis at a glance

About 85% of Cushing’s disease cases are caused by a microadenoma (a very small benign tumor) in the pituitary gland, which overproduces adrenocorticotropic hormone (ACTH). This hormone continuously stimulates the adrenal glands, leading to excessive production of cortisol (the stress hormone) and resulting in systemic symptoms. The remaining 15% are adrenal-dependent Cushing’s, caused by tumors on the adrenal glands themselves, and rarely, the condition can be iatrogenic, resulting from long-term steroid administration. It is most commonly seen in middle-aged to senior small- to medium-sized dogs, with breeds such as Dachshunds, Boxers, Boston Terriers, and Miniature Poodles being particularly predisposed.

Suspect Cushing’s if you notice these signs

Cushing’s disease symptoms develop gradually, making it easy for pet owners to dismiss them as normal signs of aging. If you notice two or three of the following signs occurring together, we recommend hormone testing. - Increased thirst and urination: Drinking significantly more water than usual and producing larger volumes of urine. - Increased appetite: Continuously appearing hungry even after being fed. - Pot-bellied appearance: The abdomen becomes distended and hangs down like a balloon. - Hair loss and thinning skin: Symmetrical hair loss on both sides of the body, accompanied by thinning skin and the development of dark spots. - Panting: Frequent panting even when it is not hot. - Muscle weakness: Difficulty climbing stairs or jumping.

Illustration of a dog showing suspected symptoms of Cushing's disease

When to seek immediate veterinary care

Cushing’s disease typically progresses slowly, but the sudden onset of neurological symptoms may indicate a pituitary macroadenoma—a large tumor that presses on surrounding brain tissue. If your pet experiences stumbling, circling to one side, seizures, sudden vision loss, or lethargy lasting more than 24 hours, seek veterinary care immediately. An MRI may be necessary.

How is Cushing’s disease diagnosed?

Diagnosing Cushing’s disease isn’t a one-step process; it typically involves two to three stages. First, routine blood and urine tests are used to identify clues such as elevated liver enzymes (specifically ALP) and low urine specific gravity. Next, hormone tests are performed to confirm the diagnosis, with the most commonly used being the ACTH stimulation test and the low-dose dexamethasone suppression test. Once confirmed, abdominal ultrasound or CT/MRI imaging is used to determine the tumor’s location—whether it’s in the pituitary gland or the adrenal glands. This distinction is crucial for determining the appropriate treatment plan.

Comparison of key diagnostic tests

Item	ACTH Stimulation Test	Low-Dose Dexamethasone Suppression Test	Abdominal Ultrasound
Purpose	Confirm cortisol response	Confirm negative feedback	Measure adrenal size
Accuracy	Moderate	High	Supplementary
Time Required	About 1 hour	8-hour hospitalization	20–30 minutes
Treatment Monitoring Possible	True	False	False

Test selection depends on the dog's condition and the clinic's environment. Decide in consultation with your veterinarian.

Treatment options — Trilostane as the first-line choice

The first-line treatment for canine Cushing’s disease is currently an oral medication called trilostane. It works by inhibiting the enzyme responsible for cortisol production in the adrenal glands, thereby regulating hormone levels back to a normal range. According to veterinary pharmacology textbooks, most dogs experience a reduction in excessive thirst and urination within about one month, with skin symptoms gradually improving as well. The dosage is determined by the veterinarian based on the dog’s weight and test results. To monitor the response, an ACTH stimulation test is performed 10–15 days, one month, and three months after starting treatment. Thereafter, regular check-ups are conducted every three to six months.

An illustration of a pet owner giving medicine to a puppy.

Surgery and radiation therapy — When to consider them?

If the pituitary tumor is large enough to cause neurological symptoms, known as a macroadenoma, medication alone may not be sufficient. In such cases, radiation therapy should be considered, with the goal of reducing tumor size to relieve pressure on the nerves. For adrenal-dependent Cushing's disease, where the tumor is located in the adrenal gland itself, surgical removal of the adrenal gland can be a definitive treatment. Hormone levels are stabilized with trilostane before and after surgery. Pituitary surgery is available at very few hospitals in Korea.

Key home care points to monitor

Once medication begins, there are specific signs you should monitor daily. - Track water intake and urine output: Note weekly whether these amounts are decreasing. - Changes in appetite: A sudden loss of appetite may indicate the dosage is too high. - Vomiting, diarrhea, or lethargy: Stop the medication immediately and contact your veterinarian. - Weight monitoring: Weigh your pet at the same time every two weeks. - Regular hormone testing: Do not miss scheduled tests, which should be performed every 3 to 6 months.

An illustration of a pet owner checking on their senior dog at home

How to recognize medication side effects

Trilostane is generally well-tolerated, but in rare cases, it can cause a side effect of excessively low cortisol levels (hypocortisolism). If your pet suddenly shows lethargy, loss of appetite, vomiting, diarrhea, and tremors at the same time, stop the medication immediately and contact your veterinarian. In emergency situations, intravenous fluids and steroid supplementation may be required. Do not adjust the dose on your own; always modify it based on test results.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently asked questions

How long can a dog with Cushing’s disease live?

The median survival time for dogs with pituitary tumors is reported to be approximately 750 days (about two years), though some studies show that certain dogs maintain their quality of life for even longer. Prognosis varies significantly depending on the timing of diagnosis, tumor size, and the presence of concurrent conditions, making regular check-ups essential.

Will my pet need to take medication for the rest of its life?

Yes, trilostane doesn’t eliminate the tumor itself; it regulates excess hormone production, so lifelong administration is the standard. If you stop the medication on your own, symptoms can quickly return.

Which is better, trilostane or mitotane?

Recently, trilostane has become the first-choice treatment more often. Mitotane is considered only in specific cases or when trilostane doesn’t work well, because although it has a strong effect, managing its side effects can be challenging.

Is an MRI absolutely necessary?

If there are no neurological symptoms and the response to medication is good, management without an MRI is possible. However, if neurological signs such as ataxia or seizures occur, an MRI is recommended to confirm the presence of a macroadenoma.

Is there a specific diet that’s good for dogs with Cushing’s disease?

Avoid high-fat and high-sodium foods, and opt for a balanced diet with appropriate protein levels. Since Cushing's disease can be accompanied by metabolic disorders such as diabetes, always consult your veterinarian before changing your pet's diet.

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References

[1] Warman S., The dog with hyperadrenocorticism, in 100 Top Consultations in Small Animal General Practice, Ch. 74

[2] BSAVA Manual of Canine and Feline Dermatology, 4th Ed — Hyperadrenocorticism (Trilostane therapy section)

[3] Clinical Medicine of the Dog and Cat, 4th Ed — Trilostane therapy in adrenal disease

[4] Perez-Alenza D., Trilostane dosing in canine hyperadrenocorticism, 2017