강아지 부신수질종양(크롬친화세포종) 증상과 원인, 진단·치료와 관리 포인트 총정리

If Your Dog Suddenly Panting and Trembling — From Symptoms to Treatment of Adrenal Medullary Tumors

EndocrineDiseasesMeongsiljang Veterinary Advisory Board

Adrenal medullary tumors (pheochromocytomas) in dogs are rare malignant tumors that arise in the adrenal medulla. They can cause high blood pressure, heart problems, and anxiety due to excessive secretion of adrenaline and noradrenaline. Early diagnosis and appropriate treatment are essential.

What Are Adrenal Medullary Tumors (Pheochromocytomas) in Dogs?

Diagram of a dog's adrenal gland, highlighting the medulla

Adrenal medullary tumors (pheochromocytomas) are rare tumors that arise from chromaffin cells in the adrenal medulla. Most are benign, but in rare cases they can become malignant, invading the caudal vena cava or metastasizing to the lungs, liver, or bones. These tumors cause a variety of symptoms by excessively secreting catecholamines (epinephrine and norepinephrine), including high blood pressure, rapid or irregular heart rate, weakness, fainting, and anxiety-related behaviors. Because symptoms are often transient and vague, early detection can be challenging. As the tumor progresses, cardiovascular complications may develop, so it is important to seek accurate diagnostic testing and veterinary care if you suspect this condition. Carefully monitor your pet for even subtle changes in their health.

What Are the Main Causes of Pheochromocytoma?

The exact cause of pheochromocytoma has not yet been clearly identified. It remains unclear what triggers tumors in the adrenal glands to secrete catecholamines, even in otherwise normal adrenal tissue. However, adrenal tumors tend to be diagnosed more frequently with advancing age, so older dogs require particular vigilance. Pheochromocytomas can occur as solitary tumors or, rarely, as part of multiple endocrine neoplasia syndrome, which involves tumors in several endocrine glands simultaneously. Based on current evidence, it is difficult to definitively attribute the cause to specific breeds or sexes. Given the complexity of the underlying mechanisms, early detection through regular health screenings is more important than pinpointing a single cause.

A scene of a puppy receiving a check-up from a veterinarian.

Check the Main Symptoms and Signs

Adrenal medullary tumors are difficult to detect early because their symptoms are often transient and vague. The main symptoms caused by excessive secretion of catecholamines include the following:

Hypertension and its effects: Weakness, fainting (syncope), and vision problems due to retinal hemorrhage may occur.

Cardiac issues: Heart rate may increase (tachycardia) or become irregular, and breathing may become rapid.

Anxious behavior: Sudden restlessness, pacing, and muscle tremors may appear.

Lethargy and decreased appetite: A tendency toward low energy and reduced appetite is common.

Increased water intake and urination: Drinking more water and urinating more frequently.

Vomiting and diarrhea: Gastrointestinal symptoms may also occur.

If these symptoms recur or persist, a veterinary visit is necessary.

Emergency Signs Requiring Immediate Veterinary Visit

Sudden fainting or collapse, severe difficulty breathing, a rapid or irregular heartbeat, pale mucous membranes, and poorly controlled severe hypertension can all be life-threatening. If you notice any of these emergency signs, don’t wait—seek veterinary care immediately.

Diagnostic Tests for Accurate Diagnosis

To accurately diagnose an adrenal medullary tumor, multiple tests are required. - Blood tests: Measure the concentrations of catecholamines and their metabolites (metanephrine and normetanephrine) in plasma to check for excessive secretion. - Urine tests: Analyze the ratio of urinary normetanephrine and metanephrine to creatinine. If this ratio is more than approximately four times the upper limit of normal, a tumor is strongly suspected. Imaging studies (ultrasound, CT, MRI) are used to determine the tumor’s location, size, and whether it has invaded surrounding tissues or blood vessels. CT is particularly sensitive and accurate for assessing local invasion. To confirm that the tumor is functional, quantitative testing of catecholamines and their metabolites is essential. A comprehensive combination of tests is necessary for an accurate diagnosis.

Treatment Methods and Step-by-Step Approach

Treatment for adrenal medullary tumors depends on the tumor’s size, whether it has metastasized, and the dog’s overall health. Surgical treatment (adrenalectomy) is the definitive therapy that can completely remove the tumor. If complete resection is successful, dogs may survive for more than 18 months to over 4 years, even if a blood clot is present in the caudal vena cava. However, preoperative, intraoperative, and postoperative care are complex; before surgery, blood pressure is typically stabilized in advance using an alpha-adrenergic blocker such as phenoxybenzamine. If surgery is not feasible or if the tumor has metastasized, medical management with medications to control symptoms is attempted. After surgery, blood glucose and blood pressure must be monitored together, and regular follow-up examinations are necessary. The treatment plan should be individually tailored in consultation with your veterinarian.

A scene of a veterinarian performing surgery on a puppy.

Home Care and Daily Management

Dogs undergoing treatment need to have their stress minimized as much as possible. Provide a stable environment and maintain a consistent routine for meals and exercise. Administer medications exactly as directed by your veterinarian. Monitor blood pressure regularly, and promptly record and report any changes to the clinic. If symptoms worsen—such as fainting or difficulty breathing—seek immediate veterinary care. Consistency in daily management significantly impacts recovery and survival. Your family’s attention and involvement are essential.

A dog resting in a calm and stable environment

Preventing Recurrence and Breed-Specific Precautions

Adrenal medullary tumors can metastasize to the lungs, liver, and bones if malignant, making regular follow-up examinations essential even after surgery. While it is difficult to definitively determine breed-specific incidence rates based on current evidence, adrenal tumors are more commonly detected as dogs age, so extra caution is warranted in senior dogs. The sooner you check for suspected symptoms, the better.

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 an adrenal medulla tumor treatable?

If surgery is an option, the chances of successful treatment are high. The treatment plan will vary depending on the size of the tumor and whether it has spread. If surgery is not feasible, symptoms can be managed with medication.

Does this disease only occur in dogs?

It primarily occurs in dogs, but it is also rarely reported in cats. In fact, it is much less common in cats.

How long does the recovery period after surgery take?

Recovery time varies from pet to pet. Because preoperative, intraoperative, and postoperative care require meticulous attention, it’s important to restrict your pet’s activity, monitor blood pressure and blood sugar levels, and schedule regular veterinary check-ups during the recovery period. The exact duration will be determined in consultation with your veterinarian, based on the tumor’s condition and how the surgery progresses.

Is medication alone sufficient?

If a tumor cannot be removed surgically, medication becomes the primary treatment. However, when surgery is an option, it offers a more definitive solution.

Can it be prevented?

Although the exact cause remains unknown, making prevention difficult, early detection is possible through regular health check-ups.

Comparison of Pheochromocytoma Treatment Options

Item	When appropriate	Efficacy level	Side effects/characteristics
Surgical treatment (adrenalectomy)	When the tumor is localized and there is no metastasis	High (curative treatment)	Pre-, intra-, and post-operative management is challenging
Preoperative drug stabilization	When blood pressure needs to be controlled in advance before surgery	Important for blood pressure stabilization	Blood pressure reduction with an α-blocker (phenoxybenzamine)
Medical (drug) management	When surgery is difficult or metastasis is present	Symptom relief level	Controls symptoms and blood pressure with medication

Treatment is determined by your veterinarian based on the individual situation. A consultation after a hospital visit is needed.

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References

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

[2] Plumb's Veterinary Drug Handbook, 9th ed. (2022). Wiley-Blackwell.

[3] Hoffman J, et al. (2020). Pheochromocytoma in dogs: A retrospective study of 42 cases. Journal of Veterinary Internal Medicine, 34(3), 1120–1128.