A pheochromocytoma is a tumor of the chromaffin cells of the adrenal medulla that can release norepinephrine and epinephrine in unpredictable bursts. It is uncommon in dogs and often found by chance on abdominal ultrasound. It matters because the catecholamine surges can cause collapse, arrhythmias and hypertensive crises, the tumor often grows into the caudal vena cava, and adrenalectomy is a high-risk operation that needs careful preparation.
Key facts
Pheochromocytoma at a glance- Species / system: Dog; adrenal medulla (endocrine).
- Cause: Neoplasia of medullary chromaffin cells, which secrete catecholamines without normal control.
- Classic presentation: An older dog with episodic weakness, collapse, panting or restlessness, tachyarrhythmia and hypertension, plus an adrenal mass that may extend into the caudal vena cava. Many dogs have no signs.
- Diagnosis: Plasma free normetanephrine or urine normetanephrine:creatinine ratio with an adrenal mass on imaging. Histopathology confirms.
- Treatment: Alpha-blockade (usually phenoxybenzamine), then adrenalectomy. A beta-blocker is added only after alpha-blockade.
- Not zoonotic or reportable.
What's inside
11 sections in the full guide- Key facts
- How the NAVLE tests this
- Cause and pathophysiology
- Clinical signs
- Diagnosis
- Differential diagnoses
- Treatment and management
- Prognosis
- Quick review
- Test yourself
- References
The full guide also has 4 tables, 3 figures, 3 self-test questions and 22 references, available to NAVLE members.
Read the full study guide
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