SURGICAL TREATMENT
1. An adrenal tumor. Note the large size, coarse appearance of the capsule, and invasion of the gland into surrounding structures.
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For cats with unilateral aldosterone-secreting adrenal masses and no detectable metastatic disease, the preferred treatment
is surgical excision3,4 based on reports with successful interventions (Figures 1 & 2).1,5-7 Successful surgery can be curative for both adenomas and adenocarcinomas, and signs of hypokalemia and hypertension often
resolve without further treatment or medical management.1,5-7
Preoperative medical therapy
2. A unilateral adrenal adenoma. The well-circumscribed tan-colored tissue is the adenoma, which was confirmed with histopathologic
examination. The rest of the adrenal tissue architecture was normal.
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Correcting hypokalemia and controlling hypertension with medical management (Table 1) are recommended to increase anesthetic, perioperative, and postoperative stability. In one case report, all cats that underwent
surgery (n=10) had a successful preoperative stabilization period ranging from 14 to 149 days of medical management.5 All cats meeting the criteria for surgical managment that were hypertensive at presentation became normotensive when treated
before surgery.5 Potassium concentrations of hypokalemic cats receiving oral supplementation before surgery increased in all cases but did
not normalize by the time of surgery; however, cats that presented with a myopathy showed resolution of these clinical signs
despite the persistent hypokalemia.1,5,8
Perioperative complications
Reported perioperative complications include six cases of intra-abdominal hemorrhage, one case of acute renal failure, one
case of sepsis, and one case of suspected thromboembolism.5,6,8,9
Sepsis and thromboembolism have been reported after adrenalectomy for other conditions, but hemorrhage has been reported more
frequently in cats undergoing adrenalectomy for primary hyperaldosteronism.5,6,9 Further studies are necessary to assess risk factors associated with poor outcomes.
Postoperative care
After surgery, blood pressure measurements and potassium concentration monitoring should be evaluated upon recovery and repeated
at least once a day for the initial 48 hours after surgery. Ideally, the potassium concentration should be checked every six
hours for the first 24 hours after surgery until values stabilize or the patient begins to eat, in which case, oral supplementation
can replace intravenous replacement.
Adjustments to the antihypertensive therapy and potassium replacement therapy (potassium concentration in intravenous fluids
or oral supplementation dose) should be made according these results. If the patient remains hypertensive or hypokalemic by
the time of discharge, oral therapy to correct the condition should be continued, and the patient should be rechecked within
five days.
In reported cases in which cats survived surgical intervention, spironolactone and amlodipine therapy were discontinued the
day of surgery without the need to reinstitute therapy postoperatively.1,5
Normokalemia after successful adrenalectomy was documented within six days in most cases5,6 and on postoperative day 13 in one case.1 Oral potassium supplementation doses should be tapered until and ultimately discontinued when the serum concentration normalizes.
Once blood pressure and potassium concentrations are stable without the need for medical intervention and the owner reports
resolution of clinical signs associated with hypertension or hypokalemia, no further rechecks or follow-up are necessary.
PROGNOSIS
The prognosis in cats with completely excised unilateral nonmetastatic adrenocortical neoplasia that survive the perioperative
period without complication is excellent without the need for life-long medication in most cases.3-5,7 In cats, adrenal adenocarcinomas do not appear to be associated with a poorer prognosis than adrenal adenomas.5 The reported survival time for medically managed cats with primary hyperaldosteronism ranges from several months to many
years.1,4,5
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