A pheochromocytoma is a tumor of the adrenal gland, which causes the glands to make too much of certain hormones. This can cause an increase in heart rate, blood pressure, and breathing rate. These symptoms are intermittent because the hormones that cause them are not made all of the time or are made in low amounts.
These tumors are rare in dogs. They commonly spread to organs near them and can rapidly metastasize to other areas of the body.
