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Adrenal Gland Tumors in Dogs

What Are Adrenal Gland Tumors in Dogs?

The adrenal glands, situated just in front of the kidneys in your dog’s abdomen, can develop tumors in any part, which may or may not be cancerous. These tumors can be benign, meaning noncancerous, yet still hormonally active, leading to various symptoms.

Crucial for regulating heart rate, blood sugar, blood pressure, and hormone secretion during physical and emotional stress, a dog’s adrenal glands consist of two parts: the cortex and the medulla. The cortex, divided into three layers, produces steroid hormones including mineralocorticoids (like aldosterone), glucocorticoids (such as cortisol), and sex hormones (like estrogen, progesterone, and testosterone). On the other hand, the medulla secretes catecholamines, crucial during stress and fight-or-flight responses, including epinephrine (adrenaline) and norepinephrine.

The most common adrenal tumor-related disease is adrenal-dependent hyperadrenocorticism, also called Cushing’s disease. Symptoms of Cushing’s disease in dogs include excessive thirst, urination, and appetite. Although Cushing’s disease is prevalent among dogs, the majority develop it due to pituitary gland dysfunction, not adrenal issues. Only about 20% of dogs with Cushing’s disease have an adrenal tumor.

Less common tumors of the adrenal glands may produce aldosterone, leading to a condition known as hyperaldosteronism, which can manifest as weakness and lethargy. Some more serious rare tumors of the adrenal glands can infiltrate major blood vessels, resulting in arrhythmias, clots, and a significant increase in blood pressure.

The primary types of adrenal tumors found in dogs are:

  • Adrenal adenoma: This tumor can be either functional (secreting hormones) or nonfunctional (not secreting hormones). Adenomas often secrete cortisol, contributing to Cushing’s disease, or aldosterone, leading to hyperaldosteronism.
  • Adrenal carcinoma: A malignant tumor capable of secreting cortisol or aldosterone, causing Cushing’s disease or hyperaldosteronism. These tumors metastasize in up to 50% of cases, typically spreading to the liver and lungs.
  • Pheochromocytoma: An infrequent tumor located in the medulla that secretes epinephrine, norepinephrine, or both.
  • Paraganglioma: A rare tumor originating from the nerves that can release catecholamines.

Most adrenal gland tumors occur in middle-aged to older dogs, with no specific breed predispositions. Larger dogs might have a higher risk of developing functional tumors that secrete cortisol, leading to Cushing’s disease.


The symptoms of adrenal gland tumors in dogs vary depending on the type of tumor present. Typically, tumors that secrete cortisol, a steroid hormone, result in the following symptoms:

  • Increased thirst
  • Increased urination
  • Increased appetite
  • Weight gain
  • Distended abdomen
  • Skin problems
  • Urinary tract infections
  • Hair loss

More severe tumors, such as pheochromocytomas, release adrenaline and other fight-or-flight hormones. These symptoms can be intermittent and nonspecific, and at times the dog may appear normal. However, these tumors can lead to significant cardiac issues and other symptoms including:

  • Irregular heart rate and rhythm leading to weakness and collapse
  • Elevated blood pressure resulting in changes in behavior or vision loss
  • Increased thirst and urination
  • Weight loss and reduced appetite
  • Seizures
  • Excessive panting
  • Fever
  • Coughing
  • Gastrointestinal disturbances

Tumors that secrete aldosterone cause high blood pressure and low potassium levels, which may lead to the following signs:

  • Weakness
  • Vision loss due to high blood pressure
  • Lethargy
  • Hind leg weakness or collapse
  • Unusual neck positioning


The causes of adrenal gland tumors in dogs are largely unknown. While there may be a genetic inclination towards these tumors, environmental factors, dietary habits, or medications might also contribute to certain animals being more susceptible to developing them. Further studies and research are necessary to gain a deeper understanding of the origins of these conditions.


Veterinarians diagnose adrenal gland tumors in dogs primarily through ultrasound imaging, which helps assess the size, shape, and structure of the tumors. Although ultrasound can confirm the presence of adrenal tumors, it may not definitively identify the tumor type.

Benign adenomas are typically small and non-invasive, while carcinomas tend to be larger and can invade surrounding tissues. Generally, tumors affect only one adrenal gland, not both. While a biopsy provides a definitive diagnosis, not all dogs are suitable candidates for this procedure.

In addition to ultrasound and biopsy, veterinarians rely on various diagnostic tests to evaluate adrenal tumors, considering the clinical signs and disease severity. These tests include:

  • Routine blood chemistry and complete blood count
  • Blood pressure measurements
  • Chest and abdominal X-rays to assess cancerous spread
  • Cardiac consultation to exclude heart failure
  • Advanced imaging techniques to determine tumor invasiveness
  • Hormone testing
  • Endocrine testing, such as an ACTH Stimulation test or Low-Dose Dexamethasone Suppression Test


Treatment for adrenal gland tumors in dogs typically involves the removal of the affected adrenal gland through a procedure known as adrenalectomy. However, surgery may not be feasible if the tumor has invaded major blood vessels or other organs, or if it has spread to distant sites (metastasis). Adrenalectomy is a complex surgery and should be performed by a surgical specialist at a 24-hour facility, as complications during and after surgery are common. For dogs who are not suitable candidates for surgery, medical management may offer benefits for a certain period. Nonetheless, fatal complications such as blood clots and arrhythmias can arise unexpectedly.

Dogs with adrenal-dependent Cushing’s disease may experience clinical improvement with medications like mitotane or trilostane, which work to suppress cortisol production. For dogs with nonresectable pheochromocytomas, medications to address their clinical symptoms such as high blood pressure or cardiac arrhythmias may be beneficial.

Dogs with nonresectable adrenal tumors that secrete aldosterone may benefit from medications like spironolactone, which help block aldosterone receptors.

Supportive care may be necessary during acute crises. Many dogs may require hospitalization with intravenous fluids, medications, and supplements to manage their condition effectively.

Living and Management

The prognosis for dogs with benign, nonfunctional tumors is generally the most favorable, followed by those with benign, functional tumors. Hyperaldosteronism, though rare, typically carries an uncertain prognosis.

Cushing’s disease, often stemming from a benign tumor, can be effectively managed through surgery or medication followed by regular examinations and testing. Dogs whose symptoms are well-controlled tend to have a positive prognosis.

In cases where malignant tumors lead to Cushing’s disease, the prognosis is less optimistic, given the relatively high rates of metastasis. Some dogs may survive for several years post-diagnosis and adrenal removal, while those managed solely with medication typically survive just over a year.

Dogs diagnosed with pheochromocytomas face a guarded to poor prognosis due to their invasive and metastatic nature, often accompanied by severe side effects that impact quality of life. Approximately 20-30% of dogs may not survive the tumor removal surgery. Among those that do, the average survival time is around 1 year, with less than 60% surpassing the 3-year mark. Survival rates tend to decrease as the tumor size increases.

Adrenal Gland Tumors in Dogs FAQs

Do adrenal gland tumors in dogs cause pain?

The tumors themselves are unlikely to cause pain in dogs. However, complications arising from the tumors may lead to discomfort and a reduced quality of life.

How concerning is a tumor on the adrenal gland?

While some tumors can be life-threatening, most are less severe but still necessitate medical attention and intervention.

What is the life expectancy of dogs with adrenal cancer?

The life expectancy of dogs with adrenal cancer varies depending on the type of tumor and the chosen treatment, ranging from months to potentially years.

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