강아지 부신 종양 자주 묻는 질문 Q&A — 보호자가 꼭 알아야 할 핵심

What Are Adrenal Tumors in Dogs? — Essential Q&A on Symptoms, Diagnosis, and Treatment for Pet Owners

Oncology/CancerQ&AMeongsiljang Veterinary Advisory Board

Adrenal tumors in dogs often show few symptoms in the early stages, making early detection difficult. Here’s a summary of key information every pet owner should know.

What Are Adrenal Tumors in Dogs?

An anatomical illustration showing a tumor in a dog's adrenal gland

Adrenal tumors in dogs are growths that develop in the adrenal glands (specifically the adrenal cortex) and cause adrenal dysfunction. The most common type is a functional (hormone-secreting) tumor that excessively produces cortisol. These tumors can be benign adenomas or malignant adenocarcinomas, with roughly equal proportions of each. Some are non-functional tumors that do not secrete hormones. Approximately 15% of naturally occurring hyperadrenocorticism (Cushing’s disease) cases in dogs originate from such adrenal tumors. The condition is more frequently seen in middle-aged to senior dogs, with higher risk in breeds such as Dachshunds, Boxers, Boston Terriers, and Miniature Poodles. Because symptoms progress gradually and can be difficult to detect in the early stages, regular veterinary check-ups are essential. Veterinarians suspect and differentiate adrenal tumors through blood tests and abdominal ultrasound, as this is a condition that can affect the entire body.

What Are the Main Causes of Adrenal Tumors?

The exact cause of adrenal tumors remains unclear. However, Cushing’s disease is more common in middle-aged to senior dogs, and certain breeds such as Dachshunds, Boxers, Boston Terriers, and Miniature Poodles are known to have a higher risk, suggesting that age and breed predisposition may play a role. Abnormal proliferation of adrenal cortex cells leads to excessive or unregulated secretion of hormones like cortisol, which can cause various systemic effects. Because the disease progresses slowly and gradually, early signs are often difficult to detect. While there is no established method for prevention, regular health check-ups can aid in early detection, significantly improving diagnosis and treatment outcomes.

A microscopic image showing abnormal cell proliferation in adrenal tissue

What Are the Main Symptoms of Adrenal Tumors?

Symptoms of adrenal tumors vary depending on whether they secrete hormones. Functional tumors that produce cortisol cause Cushing’s disease (hyperadrenocorticism), leading to increased thirst and urination (polyuria/polydipsia, PU/PD), increased appetite (polyphagia), abdominal distension (pot-bellied appearance), lethargy, muscle weakness, panting, thinning skin, and symmetrical hair loss. Non-functional tumors, which do not secrete hormones, often show no obvious signs in the early stages, which can delay detection. Malignant adrenal tumors, in particular, can invade nearby blood vessels, such as the phrenicoabdominal and caudal vena cava. If the tumor penetrates these vessels, sudden internal bleeding into the abdominal cavity can occur, potentially leading to shock. If your pet experiences recurrent excessive thirst and urination, prompt veterinary examination is recommended. By the time symptoms become pronounced, the tumor has often progressed, making early diagnosis essential.

A dog weakened by an adrenal tumor, exhibiting abdominal distension and muscle weakness

Signs Requiring Immediate Veterinary Care

If your pet suddenly becomes lethargic and loses its appetite, experiences repeated vomiting or diarrhea, has pale gums, collapses into shock, or becomes disoriented, seek veterinary care immediately. Malignant adrenal tumors can invade nearby blood vessels, causing sudden internal bleeding into the abdominal cavity, which can lead to a life-threatening emergency. Additionally, if your pet shows excessive urination, increased appetite, and abdominal distension, it is best to have it examined as soon as possible.

How Are Adrenal Tumors Diagnosed?

Adrenal tumors are diagnosed through a comprehensive combination of tests. First, blood tests evaluate hormone levels, such as cortisol. Functional tests, including the ACTH stimulation test and the high-dose dexamethasone suppression test (HDDST), are then used to confirm Cushing’s disease (hyperadrenocorticism) and identify its underlying cause. Abdominal ultrasound assesses the size and shape of the adrenal glands and checks whether the tumor has invaded nearby blood vessels or tissues, helping to differentiate between pituitary-dependent and adrenal-dependent causes. If necessary, CT or MRI scans provide more precise details on tumor size, vascular invasion, and potential metastasis. However, while imaging reveals the tumor’s location, it cannot determine whether the tissue is overproducing hormones. Ultrasound-guided fine-needle aspiration (FNA) can identify the tumor’s origin, such as whether it arises from the adrenal cortex, but it is difficult to distinguish between benign and malignant tumors based on this method alone. An accurate diagnosis is essential for developing an effective treatment plan.

A veterinarian performing an ultrasound on a dog's abdomen.

What Are the Treatment Options for Adrenal Tumors?

Treatment for adrenal tumors depends on the tumor’s nature, location, and whether it has metastasized. For functional adrenal tumors, surgery to remove the affected adrenal gland (adrenalectomy) is the primary treatment option. However, if the tumor is large, has invaded nearby blood vessels or organs, or has metastasized, surgery may be difficult. Even when performed by an experienced surgeon, the risk of complications and mortality before and after surgery is relatively high, so the decision must be made carefully. If surgery is not feasible or additional treatment is needed, medical management with drugs such as mitotane (o,p'-DDD) or trilostane can be used to control excessive cortisol secretion. The most appropriate treatment should be determined individually in consultation with your veterinarian, taking into account the tumor’s condition and the patient’s overall health, and regular check-ups and monitoring are essential throughout the treatment process.

A dog recovering after adrenal tumor surgery

Comparison of Treatment Methods

Item	When Applied	Efficacy	Side Effects
Surgery (adrenalectomy)	When the tumor is localized and resectable	High (curative outcome expected with complete removal)	Relatively high risk of perioperative complications and death
Mitotane (o,p'-DDD)	When surgery is difficult or metastasis is present	Controls excessive cortisol secretion	Possible side effects such as adrenal cortex damage; monitoring required
Trilostane	When control of hormone excess symptoms is needed	Inhibits cortisol synthesis	Requires regular dose adjustment and monitoring

Surgery is considered the first-line treatment for functional adrenal tumors, while mitotane and trilostane are medical management options that control excessive cortisol secretion. The treatment method varies depending on the tumor's size, location, and presence of metastasis as well as the patient's condition, so it should be decided after consulting a veterinarian.

Home Care Points

Medication must be administered exactly as prescribed. Keep a consistent record of your pet’s food and water intake, and adjust their activity level appropriately. To minimize stress, maintain a quiet environment and a regular daily routine. If any side effects from the medication appear, contact your veterinarian immediately. Do not neglect regular check-ups and veterinary visits. Thorough care at home plays a significant role in enhancing treatment outcomes.

A dog resting comfortably in a quiet environment, with medication and water prepared and ready.

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

Can a dog’s adrenal tumor be treated?

It can be treated. Functional adrenal tumors can be surgically removed (adrenalectomy) or managed with medications such as mitotane (o,p'-DDD) or trilostane to control excessive cortisol production. Early detection and individualized treatment are key.

Are adrenal tumors contagious to other dogs?

No, adrenal tumors are not contagious. While there may be a genetic predisposition, they are not directly transmissible.

How long can a dog live with an adrenal tumor?

The outlook depends on the treatment approach and the tumor's condition. If the tumor can be completely removed through surgery, life expectancy may significantly increase. In other cases, it can be managed by regulating hormones with medication. However, because adrenal gland tumor surgery carries risks of complications and mortality, the prognosis varies depending on the patient's condition, so it's best to discuss the specific outlook with your attending veterinarian.

Can it be prevented?

There’s no surefire way to prevent it, but regular health check-ups can help catch it early. The older your pet gets, the more important it is to keep up with these exams.

What should I do if my pet experiences side effects during medication?

If side effects such as loss of appetite, vomiting, diarrhea, or shock occur, contact your veterinarian immediately, as medication adjustments may be necessary.

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References

[1] Plumb's Veterinary Drug Handbook, 9th Edition, 2022

[2] Veterinary Internal Medicine, 8th Edition, 2020

[3] BSAVA Manual of Canine and Feline Endocrinology, 2nd Edition, 2018