In a study of 40 dogs by Kyles, the short-term mortality rate was evaluated in regards to the presence of caval tumor thrombus. Reportedly, tumor thrombus was seen in 25% of all dogs. Eleven percent of adenocarcinomas had tumor thrombus and 55% of pheochromocytomas had tumor thrombus. As mentioned there was no difference in the perioperative death rate regardless of presence or absence of tumor thrombus. The perioperative death rate was 21% for adenocarcinomas and 18% for pheochromocytomas. Previously, pheochromocytomas patients have a high perioperative mortality rate, but the addition of protocols that include administration of high doses of phenoxybenzamine (as high as mg/kg twice daily) have reduced the death rate.
Cells of the zona fasciculata and zona reticularis lack aldosterone synthase (CYP11B2) that converts corticosterone to aldosterone, and thus these tissues produce only the weak mineralocorticoid corticosterone. However, both these zones do contain the CYP17A1 missing in zona glomerulosa and thus produce the major glucocorticoid, cortisol. Zona fasciculata and zona reticularis cells also contain CYP17A1, whose 17,20-lyase activity is responsible for producing the androgens, dehydroepiandosterone (DHEA) and androstenedione. Thus, fasciculata and reticularis cells can make corticosteroids and the adrenal androgens, but not aldosterone.