1) Pheochromocytomas, which consist of chromaffin cells, are a type of adrenal tumors; this tumor type affects the adrenal medulla instead of the cortex.
2) This tumor type causes intermittent secretion of catecholamines (epinephrine and norepinephrine); therefore the clinical signs may also be intermittent
3) A diagnostic work-up will likely include lab work, blood pressure measurement, imaging and EKG. Historically, serum inhibin used to be checked to attempt to diagnose pheochromocytomas. There are now serum and urine test that check for normetanephrine or metanephrine.
4) Clinically, dogs with this condition may present with panting, lethargy, increased thirst and urination, increased blood pressure (hypertension), increased heart rate (tachycardia) and/or irregular heart rhythms (arrhythmias) and even collapse episodes
5) The treatment of choice is surgical removal of the adrenal tumor (adrenalectomy)