What Is a Pheochromocytoma?
A pheochromocytoma is a tumor of the adrenal medulla, the inner part of the adrenal glands that sit near the kidneys. The tumor cells release stress hormones called catecholamines, mainly adrenaline (epinephrine) and noradrenaline, often in sudden bursts. These surges can raise blood pressure and heart rate to dangerous levels.
Pheochromocytomas are uncommon and are seen mostly in older dogs. They are rare in cats. They can be benign or malignant, and some grow into the large vein next to the adrenal gland (the caudal vena cava).
Why it matters
Because the signs come and go, a dog may seem completely normal at the vet. Writing down or filming episodes at home helps your vet connect the dots.
How It Differs from Other Adrenal Problems
The adrenal glands have two parts. The outer layer (cortex) is involved in Cushing’s disease, Addison’s disease, and hyperaldosteronism. A pheochromocytoma comes from the inner medulla, so it causes adrenaline-type signs rather than the thirst and hair changes typical of Cushing’s.
Signs Owners Notice
- Episodes of panting, restlessness, pacing, or anxiety
- Racing heartbeat, weakness, trembling, or collapse
- Increased thirst and urination in some dogs
- Signs of high blood pressure: nosebleeds, sudden blindness from retinal detachment, or bleeding in the eye
- Weight loss, lethargy, or a swollen belly in advanced cases
Diagnosis
Many pheochromocytomas are first found as an adrenal mass on abdominal ultrasound. Your vet will check blood pressure, run routine blood and urine tests, and may measure urine or blood metanephrines (breakdown products of adrenaline). A CT scan shows the tumor’s size and whether it has invaded nearby blood vessels, which is key for surgical planning.
Treatment and Outlook
- Pre-surgery medicine: an alpha-blocker such as phenoxybenzamine is usually given for a few weeks to control blood pressure surges.
- Adrenalectomy: surgical removal of the affected adrenal gland is the treatment of choice and is performed by an experienced surgical team.
- Medical management: for dogs that cannot have surgery, blood pressure medicines can reduce symptoms.
Dogs that come through surgery and have no spread often live comfortably for years. The surgery carries real risk, so referral to a specialty hospital is common.
Practical Tips for US Pet Owners
- Keep a log or videos of unexplained panting or collapse episodes.
- Ask for a blood pressure check during senior wellness visits.
- Ask about referral to a board-certified surgeon if an adrenal mass is found.
- Find a practice through veterinary clinic listings.
When to see a vet
Seek emergency care if your dog collapses, suddenly cannot see, or has a nosebleed with no obvious cause. Book a prompt visit for repeated episodes of panting or restlessness at rest.
Key Takeaways
- A pheochromocytoma is an adrenal medulla tumor that releases bursts of adrenaline.
- Signs are episodic and often linked to high blood pressure.
- Surgery after blood pressure control is the main treatment.
FAQ
Is pheochromocytoma the same as Cushing’s disease?
No. Both can involve adrenal tumors, but Cushing’s comes from the outer cortex and overproduces cortisol, while pheochromocytoma comes from the inner medulla and overproduces adrenaline.
Can cats get pheochromocytoma?
It is very rare in cats. Most reported cases are in dogs.
Is surgery always needed?
Surgery offers the best long-term outcome, but medicines can manage signs when surgery is not possible.