강아지 부신수질종양(크롬친화세포종) 자주 묻는 질문 Q&A — 보호자가 꼭 알아야 할 핵심

What are adrenal medullary tumors in dogs? — Pheochromocytomas, why are they dangerous?

EndocrineQ&AMeongsiljang Veterinary Advisory Board

Adrenal medullary tumors in dogs are uncommon but can cause serious hormonal imbalances. Early detection and appropriate treatment are essential.

What are adrenal medullary tumors (pheochromocytomas) in dogs?

An anatomical image showing a tumor located in the adrenal medulla of a dog.

Adrenal medullary tumors (pheochromocytomas) in dogs are relatively rare neoplasms arising from chromaffin cells in the adrenal medulla. They cause various clinical signs by secreting unregulated amounts of adrenaline and noradrenaline (catecholamines). - Adrenal medullary tumor: A relatively rare tumor originating from chromaffin cells in the adrenal medulla, which may occur as a solitary lesion or as part of multiple endocrine neoplasms. - Hormonal excess: Unregulated secretion of catecholamines can lead to hypertension and cardiac issues such as tachycardia and arrhythmias. - Middle-aged and older dogs: These tumors are primarily found in middle-aged and older dogs. Because symptoms are often nonspecific, they are frequently discovered incidentally. - Importance of early detection: Due to the diverse and episodic nature of symptoms, which can be easily overlooked, consistent monitoring and regular veterinary check-ups are essential. - Potential for metastasis: Although rare, these tumors can behave malignantly, invading the caudal vena cava or metastasizing to the lungs, liver, or bones, making accurate assessment crucial.

Why is this tumor dangerous?

This tumor can cause high blood pressure due to excessive secretion of catecholamines, which places strain on the heart and may lead to changes in the heart muscle, such as myocardial hypertrophy. - Risk of high blood pressure: Persistent or episodic high blood pressure can strain the heart and lead to complications such as retinal hemorrhage. - Cardiac strain: Rapid heart rate, arrhythmias, and changes in the heart muscle, including myocardial hypertrophy, may occur. - Episodic symptoms: Because symptoms appear and disappear in episodes, they may not be present at the time of the veterinary visit. - Potential for metastasis: Although rare, the tumor may invade the caudal vena cava or metastasize to the lungs, liver, or bones, making management more difficult. - Early management is essential: If signs such as weakness or fainting are observed, do not ignore them; work with your veterinarian to manage the condition.

An image showing a dog exhibiting symptoms of high blood pressure and a blood pressure monitor

What are the main symptoms?

Symptoms of adrenal medullary tumors in dogs are highly variable and episodic, potentially including weakness, fainting, rapid breathing, tachycardia or arrhythmias, anxiety, and sudden collapse. - Cardiovascular symptoms: Tachycardia or arrhythmias, fainting, pale mucous membranes, and retinal hemorrhages may occur. - Respiratory and systemic symptoms: Rapid breathing (tachypnea), lethargy, weakness, seizures, or muscle tremors may be observed. - Behavioral changes: The dog may appear anxious, restless, or pace around. - Gastrointestinal and systemic symptoms: Decreased appetite, vomiting or diarrhea, and polydipsia-polyuria may accompany the condition. - Acute exacerbation: If symptoms worsen suddenly, immediate veterinary attention is required. - Non-specific symptoms: Because these signs resemble those of other diseases and occur episodically, diagnosis can be challenging; therefore, consistent monitoring is essential.

A medical image of a dog showing symptoms caused by an adrenal medulla tumor

Signs requiring immediate veterinary visit

If your pet suddenly experiences shock, difficulty breathing, symptoms of heart failure, loss of consciousness, or repeated severe vomiting and diarrhea, you should seek veterinary care immediately. These signs may indicate life-threatening complications caused by an acute surge in hormones. Until you reach the clinic, keep your pet as calm and still as possible.

How is the diagnosis made?

Diagnosis is made by combining hormone metabolite measurements in blood and urine with imaging studies such as ultrasound, CT, or MRI. - Hormone metabolite testing: Elevated plasma or urinary metanephrine and normetanephrine levels are highly indicative for diagnosis. - Imaging is essential: Ultrasound is used to identify adrenal masses, while CT or MRI precisely determines the tumor’s location, size, and any invasion into surrounding tissues. - Catecholamine measurement: To confirm that the tumor is functional, quantitative analysis of plasma catecholamines and their metabolites is required. - Caution with biopsy: Direct manipulation of the tumor can trigger massive catecholamine release; therefore, definitive diagnosis is typically achieved through histopathological examination after tumor removal. - Multistep diagnostic approach: Multiple tests are performed concurrently to differentiate this condition from other adrenal diseases and ensure an accurate diagnosis. - Early detection is possible: If your pet exhibits unexplained episodic weakness, this tumor should be considered in the differential diagnosis.

CT scan image showing a tumor located in a dog's adrenal gland

What are the treatment options?

The primary treatment is surgical removal of the tumor (adrenalectomy), and it is essential to prepare medications to stabilize blood pressure before surgery. - Surgical treatment: Adrenalectomy to remove the tumor is the most definitive treatment. - Preoperative medication: Blood pressure is controlled with alpha-adrenergic blockers such as phenoxybenzamine, starting at least one week before surgery. - Intraoperative and postoperative care: Anesthesia and monitoring are important to prepare for complications such as arrhythmias, and postoperatively, changes such as hypoglycemia must be closely observed. - When surgery is not feasible: If resection is not possible or the owner declines surgery, symptoms can be managed with medication. - Prognostic factors: The prognosis is better when there are no intraoperative arrhythmias, the patient is younger, and complete resection is achieved. - Effect of complete resection: If the tumor is completely removed and the course is favorable, survival can extend from 18 months to over 4 years.

A veterinarian performing surgery on a dog with an adrenal medullary tumor

What can be managed at home?

After surgery, it’s important to maintain a quiet environment, minimize stress, and administer medications regularly. - Environment Management: Provide a calm, stable space to reduce stress and prevent sudden excitement. - Medication Administration: Give medications at the correct times and dosages as directed by your veterinarian. - Diet and Blood Sugar Management: Offer a balanced diet recommended by your vet, and closely monitor for signs of low blood sugar after surgery. - Blood Pressure Monitoring: Regularly check blood pressure to detect any abnormalities early. - Exercise Control: Avoid strenuous activity and limit exercise to light walks. - Regular Check-ups: Schedule regular veterinary visits to monitor for recurrence or metastasis and assess overall health.

Precautions to observe

Be mindful of potential drug interactions before and after surgery. In particular, combining antihypertensive medications with other drugs can lead to serious side effects. It is essential to strictly follow your veterinarian’s instructions regarding medication. Additionally, because tumors can recur or metastasize, regular check-ups are crucial.

Comparison of responses by symptom stage

Item	Symptom stage	Main symptoms	Response	Emergency status
Mild	Mild anxiety, rapid heart rate	Observation, blood pressure and hormone tests	Observe after consulting a veterinarian	No
Moderate	Hypertension, decreased appetite, episodic weakness	Blood and hormone tests, imaging	Start preoperative medication such as alpha-blockers	Warning
Severe	Difficulty breathing, collapse, fainting	Immediate emergency stabilization and treatment	Visit the hospital immediately	Yes

If symptoms worsen, an immediate hospital visit is needed.

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

Is canine pheochromocytoma hereditary?

The exact genetic factors have not yet been identified. It can occur as a solitary tumor or, rarely, as part of multiple endocrine neoplasia. Since it is primarily found in middle-aged and older dogs, careful monitoring is recommended.

What is the prognosis after surgery?

If the tumor is completely removed and recovery goes smoothly, some pets can live for 18 months to over 4 years. Regular check-ups after surgery are essential to monitor for recurrence.

Will medication alone be sufficient?

Medications help regulate blood pressure before and after surgery, and are used for symptom management when surgery is difficult. However, since they have limitations in eliminating the tumor itself, surgery remains the most definitive treatment.

Can it be prevented?

There is currently no definitive way to prevent this condition. The most important thing is early detection through regular monitoring and health check-ups.

Is it contagious to other dogs?

No. Adrenal medullary tumors are not contagious, and their genetic factors are not clearly defined. They do not affect other dogs.

7 Key Points for Canine Thyroid T4 Testing by Veterinarians — From Timing to Result Interpretation

7 Key Tips from Veterinarians for Managing Thyroid Nodules and Cysts in Dogs

7 Key Symptoms and Management Essentials for Canine Thyroid Cancer, Explained by Veterinarians

Clomipramine Behavior Medication Guide

Robenacoxib (Onsior): The Complete Guide to Feline NSAIDs

The Complete Guide to Toceranib (Palladia) for Dogs

Praziquantel Tapeworm Dewormer: Essential Usage Guidelines

Why Use Benazepril for Dogs? — Heart and Kidney Protection Effects and Precautions

What is Enalapril? — A Dog Heart Medication: Is It Really Necessary for Your Pet?

What is Meloxicam (Metacam)? — Key Summary of Effects and Side Effects in Dogs

References

[1] Withrow SJ, Vail DM, Page RL (eds.). Withrow and MacEwen’s Small Animal Clinical Oncology, 5th ed. Elsevier, 2013.

[2] Plumb's Veterinary Drug Handbook, 9th ed. Wiley-Blackwell, 2021.

[3] Hoffman J, et al. (2020) Pheochromocytoma in dogs: A retrospective study of 47 cases. Journal of Veterinary Internal Medicine, 34(2), 567–575.