Understanding Adrenal-Dependent Cushing’s Disease By: Yashika Sharma

 Understanding Adrenal-Dependent Cushing’s Disease: dogs deserve help too.
INTRODUCTION
Adrenal-dependent Cushing’s disease, or adrenal-dependent hyperadrenocorticism (ADH), is a serious hormonal illness in dogs. It occurs when a tumor grows on one or both of the dog's adrenal glands, which sit near the kidneys. This tumor disrupts the body's natural chemistry by constantly flooding the bloodstream with cortisol, the primary stress hormone. If it’s left untreated, chronic high cortisol levels slowly damage internal organs. This increases the risk of dangerous secondary conditions like diabetes, high blood pressure, and life-threatening blood clots [Cornell Veterinary Medicine]. ADH is important to know because it mostly affects middle-aged and older dogs. Therefore knowing the causes and signs may help extend the lifespan of your favorite little buddies.  



MAIN BODY 

Underlying Causes

The primary cause of ADH is a functional tumor in the adrenal cortex. This tumor operates completely on its own, ignoring the brain's hormonal signals to stop producing cortisol. These growths fall into two main categories, split roughly evenly down the middle. Adrenocortical adenomas are harmless tumors that stay in one place and do not spread. Conversely, adrenocortical carcinomas are malignant, cancerous tumors that can invade nearby major blood vessels and spread to the liver or lungs [Merck Vet Manual].

Common Symptoms

Excess cortisol affects nearly every organ, causing noticeable changes that worsen over time. One of the earliest signs is extreme thirst and excessive urination, affecting up to 90% of sick dogs [Schofield, 2019]. Dogs also develop an insatiable, ravenous appetite because the hormone speeds up their metabolism. This leads to a distinct "pot-bellied" appearance caused by fat moving to the abdomen, an enlarged liver, and weak abdominal muscles. Skin changes are also common, including symmetrical hair loss along the body, thinning skin, easy bruising, and hard calcium deposits [Cornell Veterinary Medicine]. Finally, high cortisol levels drain the dog's energy, causing profound muscle weakness, lethargy, and constant panting even while resting.

How It Is Diagnosed

Veterinarians use a two-step approach to diagnose ADH. First, they confirm the body is producing too much cortisol using specialized blood screening tests like the Low-Dose Dexamethasone Suppression test or an ACTH Stimulation test [AAHA]. In a dog with ADH, cortisol levels remain high even when given medication that should normally suppress them. Second, the vet localizes the source using an abdominal ultrasound or a CT scan. If the scan shows one enlarged adrenal mass and a shrunken, tiny opposite adrenal gland, ADH is confirmed. The healthy gland shrinks because the brain has stopped sending normal growth signals in an attempt to lower cortisol levels [Merck Vet Manual].

Treatment Options

Veterinary teams select treatments based on the tumor's size, type, and whether it has spread. An adrenalectomy, which is the surgical removal of the affected adrenal gland, remains the gold-standard treatment choice [Veterinary Partner]. This surgery can fully cure the dog if the mass is benign or has not yet spread. When surgery is not a viable option, vets manage the condition using a daily oral medication called trilostane. Trilostane blocks the enzyme path the body uses to manufacture cortisol, which eliminates the physical symptoms without actually shrinking the tumor [FDA]. Alternatively, vets may use mitotane, a chemotherapy drug that destroys the overactive layers of the adrenal gland [Merck Vet Manual]. For advanced, non-resectable tumors, stereotactic radiotherapy provides targeted external radiation to slow tumor growth and keep the dog comfortable.

Lifespan and Statistics

Survival outcomes vary based on the tumor type and chosen treatment path. While surgery can offer a full cure, an adrenalectomy is a high-risk operation with significant mortality risks due to the massive blood vessels surrounding the adrenal glands. For dogs managed medically with trilostane or mitotane, clinical studies show an average survival time of 2 to 2.2 years [PubMed Central]. Malignant tumors that have already grown into major veins or spread to distant organs carry a much more guarded prognosis and shorter lifespans [PubMed Central].

Why Awareness and Advocacy Matter

Educating pet owners about Cushing’s disease is crucial for improving patient outcomes. Because early symptoms, like drinking a bit more water, thinning fur, and slower movement, develop gradually. Owners often mistake them for normal signs of aging. This delay in seeking veterinary care allows the disease to advance, increasing the risk of sudden, fatal emergencies like blood clots in the lungs. Additionally, caring for a dog with ADH is a major commitment that places emotional and financial strains on a family. This highlights the true value of public advocacy, veterinary research, and support networks. Continuous funding drives the development of safer, less invasive surgical tools and better pre-operative testing. These advancements help veterinarians safely identify benign masses before operating, which ultimately saves lives and gives families more high-quality time with their pets.

CONCLUSION

Adrenal-dependent Cushing's disease is a serious hormonal condition caused by adrenal tumors that severely impacts a dog's health and daily lifestyle. While progressive symptoms like constant urination, skin deterioration, and muscle wasting damage a pet's quality of life, prompt diagnosis using blood tests and ultrasounds protects them from dangerous complications. Surgery can offer a complete cure for localized, benign masses, while daily medications successfully control symptoms when surgery is not an option. Spreading public awareness and investing in veterinary research are the best ways to catch this disease early, reduce medical risks, and help affected dogs live comfortable, happy lives.

References

  • Canine Hypercortisolism (Cushing’s Syndrome). AAHA. https://www.aaha.org/resources/2023-aaha-selected-endocrinopathies-of-dogs-and-cats-guidelines/canine-hypercortisolism-cushings-syndrome/ (accessed 2026-07-18).n b m

  • Cushing’s syndrome | Cornell University College of Veterinary Medicine. www.vet.cornell.edu. https://www.vet.cornell.edu/departments-centers-and-institutes/riney-canine-health-center/canine-health-information/cushings-syndrome (accessed 2026-07-18).

  • Laura Van Vertloo. Cushing Syndrome (Hyperadrenocorticism) in Animals. Merck Veterinary Manual. https://www.merckvetmanual.com/endocrine-system/the-adrenal-glands/cushing-syndrome-hyperadrenocorticism-in-animals (accessed 2026-07-18).

  • Shanlly, S.; Slessor, J.; Yan, W.; Jessica; Bruce, H. L.; Richard. Effectiveness of Medical Treatment on Survivability in Canine Cushing’s Syndrome: A Systematic Review and Meta-Analysis. Animals 2025, 15 (20), 2954. https://doi.org/10.3390/ani15202954.


  • FDA. Treating Cushing’s Disease in Dogs. FDA 2020.

  • Adrenal Tumor Treatment in Cushing’s Syndrome. Vin.com. https://veterinarypartner.vin.com/default.aspx?pid=19239&id=4951494&f5=1 (accessed 2026-07-18).

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