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What is feline pheochromocytoma? — Warning signs and diagnosis of chromaffin cell tumors

EndocrineQ&AMeongsiljang Veterinary Advisory Board

Feline pheochromocytoma is a rare tumor that can cause serious hormonal imbalances. Early detection and appropriate treatment are key to improving survival rates.

What is feline pheochromocytoma (chromaffin cell tumor)?

An anatomical illustration highlighting the medulla of the cat's adrenal gland

Feline pheochromocytoma is a rare tumor that originates from the chromaffin cells in the inner medulla of the adrenal gland. In rare cases, it can become malignant, spreading to the lungs, liver, and bones, or invading major blood vessels such as the caudal vena cava. This tumor causes episodic overproduction of catecholamines like adrenaline and noradrenaline, leading to high blood pressure, rapid heart rate, heart muscle enlargement, and anxiety. Elevated blood pressure can result in retinal hemorrhage. Symptoms vary depending on the tumor’s size and location, and because they often appear and disappear suddenly, they may not be present during veterinary exams, making early detection challenging. Regular health check-ups and veterinary evaluations are essential. If you notice any unusual changes in your cat, seeking prompt veterinary care can aid in early diagnosis and management.

Why is this tumor dangerous?

This tumor releases catecholamines in sudden bursts, causing high blood pressure. Because these surges are irregular, symptoms tend to come and go unpredictably. The elevated blood pressure and catecholamine stimulation place significant strain on the heart, potentially leading to heart changes such as a rapid heart rate, arrhythmias, and thickening of the heart muscle. Additionally, high blood pressure can cause bleeding in the retina, which may impair vision. Because symptoms are episodic and pets often appear normal in between episodes, early detection can be challenging. However, if your pet experiences repeated episodes of sudden weakness, collapsing, or fainting, it is essential to seek veterinary care. Delaying diagnosis can make management more difficult, so accurate diagnosis and consistent monitoring are key to minimizing risks.

A medical illustration showing brain hemorrhage caused by hypertension.

What are the main symptoms?

Symptoms of feline pheochromocytoma are highly varied and can include anxiety and restlessness, tachycardia (rapid heart rate), hypertension, lethargy and weakness, syncope or sudden collapse, vomiting, diarrhea, loss of appetite, and rapid breathing. Polyuria and polydipsia, muscle tremors, and seizures may also occur. In particular, hypertension can cause retinal hemorrhage, potentially leading to vision problems. Because these symptoms often overlap with those of other diseases and tend to appear and disappear in sudden episodes, early diagnosis can be challenging. If your cat behaves differently than usual or shows a sudden drop in activity levels, it’s wise to consider this possibility and consult your veterinarian. Consistent observation is key to achieving a timely diagnosis.

Signs requiring immediate veterinary visit

If your pet suddenly shows weakness or collapse, vision problems, seizures, rapid and labored breathing, or pale gums, seek veterinary care immediately. These signs may indicate an emergency caused by high blood pressure or excess catecholamines. Delaying treatment can be dangerous, so contact your veterinarian right away.

How is it diagnosed?

Feline pheochromocytoma is diagnosed through a combination of blood tests, urinalysis, measurement of hormones and their metabolites, and imaging studies such as ultrasound, CT, or MRI. Measuring plasma or urinary concentrations of metanephrine and normetanephrine (catecholamine metabolites) is particularly helpful for diagnosis, and LC-MS/MS is recommended for precise analysis. Imaging can identify adrenal masses, with CT being especially useful for assessing invasion into surrounding tissues. This tumor should be suspected in cases of recurrent unexplained episodic weakness or when accompanied by hypertension. Whether the tumor is functional is determined by measuring blood catecholamine and metabolite levels, and the treatment plan is then formulated based on these results.

A scene of a veterinarian performing an abdominal ultrasound on a cat.

What are the treatment options?

Surgical removal of the tumor is the most definitive treatment. However, surgery should only be performed after stabilizing hypertension for at least one week using an alpha-blocker such as phenoxybenzamine. During the procedure, careful management is required due to the risks of arrhythmia and bleeding. Postoperatively, blood glucose levels must be monitored because hypoglycemia can occur. If both adrenal glands are removed, supplementation with glucocorticoids and mineralocorticoids may be necessary to prevent adrenal insufficiency. Adrenal surgery in cats is particularly challenging, with reported perioperative mortality rates of 20–33%. If surgery is not feasible or if the owner declines it, medical management to control symptoms may be attempted.

A veterinarian preparing for surgery to remove a cat's adrenal medulla tumor.

How to manage at home

To help reduce your cat’s stress, maintain a quiet and stable environment. Encourage regular meals and adequate water intake, and administer medications at the prescribed times. Do not discontinue any medications prescribed by your veterinarian, and be sure to keep up with regular check-ups. Observe your cat daily to catch any changes in behavior or worsening symptoms. Proper care at home plays a significant role in treatment success. Depending on your cat’s health condition, environmental adjustments may be necessary, so please consult with your veterinarian.

A cozy space where your cat can rest comfortably

Comparison of responses by symptom stage

Item	Main symptoms	Management	Emergency status
Mild	Anxiety, increased heart rate (tachycardia)	Regular checkups, reduce stress, consult a veterinarian	No
Moderate	Hypertension, loss of appetite, lethargy	Start blood pressure control medication, detailed testing	Warning
Severe	Retinal hemorrhage/vision abnormalities, weakness/collapse, rapid breathing	Visit the hospital immediately, consider surgery	Emergency

Symptoms may appear and disappear in episodes, so if anything differs from normal, consult a veterinarian immediately. Prompt diagnosis and appropriate management help the prognosis.

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 feline pheochromocytoma treatable?

If the tumor is completely removed through surgery, long-term survival can be expected. However, in cats, it's difficult to guarantee a "cure" due to the risks associated with anesthesia and the possibility of metastasis. Controlling high blood pressure before surgery can help reduce the risk of complications.

Is this type of tumor common in cats?

No, this type of tumor is rare in cats. However, early detection is crucial. If you notice any suspicious symptoms, it’s essential to have your cat examined by a veterinarian.

What is the survival rate after surgery?

Adrenal gland removal surgery in cats is quite challenging, with reported perioperative mortality rates of 20–33%. However, if the tumor is completely removed and recovery goes smoothly, cats can enjoy a relatively long survival time. Regular postoperative check-ups are essential.

Will medication alone be sufficient?

Medications are primarily used as adjunctive therapy to control hypertension before surgery. The most definitive treatment is tumor removal, and medication is used to manage symptoms only when surgery is not feasible.

Is prevention possible?

There is currently no known specific preventive measure. In rare cases, it may occur as part of multiple endocrine neoplasia. Early detection through regular check-ups is the most practical approach.

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References

[1] Risbon RE, deLorimer LP, Skorupski K et al. (2006) Response of canine cutaneous epitheliotrophic lymphoma to lomustine (CCNU): a retrospective study of 46 cases (1999-2004). Journal of Veterinary Internal Medicine 20, 1389-1397.

[2] Ho NT, Smith KC and Dobromylsky MJ (2018) Retrospective study of more than 9000 feline cutaneous tumours in the UK: 2006-2013. Journal of Feline Medicine and Surgery 20, 128-134.

[3] Henry C and Herrera C (2013) Mast cell tumours in cats: clinical update and possible new treatment avenues. Journal of Feline Medicine and Surgery 15, 41-48.