Laparoscopic adrenalectomy for management of a functional adrenal tumor in a cat

Rebecca R. Smith Department of Clinical Studies, Matthew J. Ryan Veterinary Hospital, University of Pennsylvania, Philadelphia, PA 19104.

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Philipp D. Mayhew Department of Clinical Studies, Matthew J. Ryan Veterinary Hospital, University of Pennsylvania, Philadelphia, PA 19104.

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Allyson C. Berent Department of Clinical Studies, Matthew J. Ryan Veterinary Hospital, University of Pennsylvania, Philadelphia, PA 19104.

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Abstract

Case Description—A 9-year-old castrated male domestic shorthair cat was examined because of hypertension that persisted after resolution of the patient's hyperthyroidism. Bilateral hypertensive retinopathy, a systolic heart murmur, left ventricular hypertrophy, and tachycardia were present.

Clinical Findings—Biochemical analysis revealed mild hypokalemia, normonatremia, high serum creatine kinase activity, high serum aldosterone concentration, and low plasma renin activity consistent with hyperaldosteronism. Hypercalcemia with an associated high serum parathyroid hormone concentration and an exaggerated low-dose dexamethasone suppression test result were consistent with concurrent hyperparathyroidism and hyperadrenocorticism, respectively. Ultrasonographic examination revealed a markedly enlarged left adrenal gland, an abnormally small right adrenal gland, and 2 nodules in the right thyroid and parathyroid glands.

Treatment and Outcome—Laparoscopic left adrenalectomy was performed concurrently with right thyroidectomy and parathyroidectomy. Histologic evaluation revealed an adrenal cortical adenoma, thyroid adenoma, and parathyroid adenoma. The cat recovered from surgery without complications. The hypercalcemia and hypertension resolved after surgery. Follow-up echocardiography revealed improvement in the left ventricular hypertrophy. Ultrasonographic examinations performed up to 26 months after adrenalectomy showed no evidence of regrowth of the adrenal mass. The patient survived for 44 months after adrenalectomy with no signs of recurrent hyperaldosteronism or hyperadrenocorticism.

Clinical Relevance—Laparoscopic adrenalectomy may be a plausible method for the treatment of unilateral functional adrenal neoplasia in feline patients when diagnostic imaging has ruled out intravascular invasion and metastatic disease. In addition, in a feline patient with hyperthyroidism and hypertension, other endocrine glands should be investigated.

Abstract

Case Description—A 9-year-old castrated male domestic shorthair cat was examined because of hypertension that persisted after resolution of the patient's hyperthyroidism. Bilateral hypertensive retinopathy, a systolic heart murmur, left ventricular hypertrophy, and tachycardia were present.

Clinical Findings—Biochemical analysis revealed mild hypokalemia, normonatremia, high serum creatine kinase activity, high serum aldosterone concentration, and low plasma renin activity consistent with hyperaldosteronism. Hypercalcemia with an associated high serum parathyroid hormone concentration and an exaggerated low-dose dexamethasone suppression test result were consistent with concurrent hyperparathyroidism and hyperadrenocorticism, respectively. Ultrasonographic examination revealed a markedly enlarged left adrenal gland, an abnormally small right adrenal gland, and 2 nodules in the right thyroid and parathyroid glands.

Treatment and Outcome—Laparoscopic left adrenalectomy was performed concurrently with right thyroidectomy and parathyroidectomy. Histologic evaluation revealed an adrenal cortical adenoma, thyroid adenoma, and parathyroid adenoma. The cat recovered from surgery without complications. The hypercalcemia and hypertension resolved after surgery. Follow-up echocardiography revealed improvement in the left ventricular hypertrophy. Ultrasonographic examinations performed up to 26 months after adrenalectomy showed no evidence of regrowth of the adrenal mass. The patient survived for 44 months after adrenalectomy with no signs of recurrent hyperaldosteronism or hyperadrenocorticism.

Clinical Relevance—Laparoscopic adrenalectomy may be a plausible method for the treatment of unilateral functional adrenal neoplasia in feline patients when diagnostic imaging has ruled out intravascular invasion and metastatic disease. In addition, in a feline patient with hyperthyroidism and hypertension, other endocrine glands should be investigated.

A 9-year-old castrated male domestic shorthair cat weighing 6.3 kg (13.9 lb) was evaluated because of persistent hypertension. Fifteen months previously, at an annual examination, hyperthyroidism (serum total thyroxine concentration, 11.3 μg/mL; reference range, 1.0 to 4.0 μg/mL), a systolic heart murmur (grade III/VI), left ventricular hypertrophy, systemic hypertension (systolic blood pressure, 185 mm Hg), tachycardia (222 beats/min), and bilateral hypertensive retinopathy were diagnosed. Hyperthyroidism was successfully treated with radioactive iodine (I131) and did not recur. However, the cardiac abnormalities and systemic hypertension remained after resolution of the hyperthyroidism. At the time of admission for evaluation of persistent hypertension, the systolic arterial blood pressure was 230 mm Hg and the heart rate was 220 beats/min. The patient was prescribed amlodipine (0.1 mg/kg [0.045 mg/lb], PO, q 24 h) and atenolol (1 mg/kg [0.45 mg/ lb], PO, q 24 h). The cat was refractory to these medications, so further diagnostic evaluation for hypertension was performed. Biochemical analysis revealed mild hypophosphatemia (2.6 mg/dL; reference range, 3.0 to 6.6 mg/dL), mild hypercalcemia (11.3 mg/dL; reference range, 9.1 to 11.2 mg/dL), mild hypokalemia (3.1 mmol/L; reference range, 3.5 to 4.8 mmol/L), normonatremia (153 mmol/L; reference range, 146 to 157 mmol/L), high serum creatine kinase activity (979 U/L; reference range, 49 to 688 U/L), and low normal plasma renin activity (0.37 ng/mL/h; reference range, 0.14 to 3.85 ng/mL/h). Hyperparathyroidism and hyperaldosteronism were suspected, prompting evaluation of serum 25-hydroxy vitamin D concentration (114 nmol/L; reference range, 65 to 170 nmol/L), serum parathyroid hormone concentration (6.70 pmol/L; reference range, 0.0 to 4.0 pmol/L), serum parathyroid hormone-related protein concentration (0.0 pmol/L; reference range, 0.0 to 1.0 pmol/L), serum ionized calcium concentration (1.64 mmol/L; reference range, 1.0 to 1.4 mmol/L), and serum aldosterone concentration (1,513 pmol/L; reference range, 194 to 388 pmol/L). In addition, a low-dose dexamethasone suppression test was performed, results of which were consistent with hyperadrenocorticism (before dexamethasone administration, 3.8 μg/dL; 30 minutes after dexamethasone administration, 7.3 μg/dL; 60 minutes after dexamethasone administration, 8.4 μg/dL; 90 minutes after dexamethasone administration, 9.0 μg/dL).

Abdominal ultrasonography revealed a markedly enlarged left adrenal gland (10 mm in width at its widest point) that was hypoechoic with an echogenic rim. The right adrenal gland was judged to be abnormally small (2 mm in width at its widest point). Ultrasonographic examination of the right thyroid and parathyroid glands revealed a hypoechoic nodule within the cranial part (3.2 × 4 mm) and a hypoechoic nodule within the caudal part (2.3 × 2.7 mm). It was not possible to determine whether the nodules seen were thyroid or parathyroid in origin. The left thyroid and parathyroid glands were judged to be normal. Although a CT scan was planned, it was not performed because of anesthetic concerns regarding the patient's severe hypokalemia (2.3 mmol/L; reference range, 3.5 to 4.8 mmol/L). No evidence of metastasis was found on thoracic radiographs, and no evidence of local invasion of vascular or other surrounding tissues was seen during abdominal ultrasonography. Therefore, surgery was scheduled for LA on the left side concurrent with a right thyroidectomy and parathyroidectomy. To increase the patient's serum potassium concentration before surgery, the patient was discharged with a 2-week course of potassium supplementation (4 mEq of potassium gluconate, PO, q 8 h) and spironolactone (1 mg/kg, PO, q 12 h). Trilostane was not given for treatment of the hyperadrenocorticism because the skin was not thin, there was no polydipsia or polyuria, and the patient was not diabetic.

Successful standard thyroidectomy and parathyroidectomy on the right side were performed first with the cat in dorsal recumbency. The 2 nodules seen on ultrasonographic examination of the thyroid and parathyroid glands were seen at surgery, but it was difficult to tell whether they were of thyroid or parathyroid gland origin. In preparation for LA, hair was clipped from 1 inch cranial to the xiphoid process to 1 inch caudal to the pubis and laterally to the most dorsal third of the body wall on the right and to the dorsal midline on the left. A routine aseptic surgical scrub of the entire area was performed. The surgeon stood on the right side of the cat with the endoscopic tower located directly across on the left side of the cat. Initially, the cat was placed in almost dorsal recumbency but with a slight tilt to the right side. A 3-portal technique was used. A 6-mm trocar-cannula assembly was used to establish a telescope portal on the ventral midline in a subumbilical location by use of a modified sutureless Hasson technique.1 Carbon dioxide pneumoperitoneum was established with a mechanical insufflator up to a maximal intra-abdominal pressure of 10 to 12 mm Hg. A 5-mm 30° telescopea was introduced through this portal. Superficial exploration of the abdominal cavity that did not involve extensive manipulation of the viscera was performed after camera placement. Subsequently, the cat was rotated into lateral recumbency for placement of the instrument portals. The first instrument portal was established with a 6-mm threaded trocarless cannulab in the left cranial abdominal quadrant, approximately 8 cm cranial to and 5 cm lateral to the subumbilical port on the left side in a location just caudal to the costal arch (Figure 1). The second instrument port was established with a 10-mm trocar-cannula assembly 3 cm caudal to and approximately 5 cm lateral to the subumbilical port in the lower left quadrant.

Figure 1—
Figure 1—

Photograph showing port placement for LA in a 9-year-old castrated male domestic shorthair cat with concurrent hyperparathyroidism and hyperadrenocorticism. A 3-portal technique was used with the camera portal located in a subumbilical position. Instrument ports are established in the left cranial and caudal abdominal quadrants.

Citation: Journal of the American Veterinary Medical Association 241, 3; 10.2460/javma.241.3.368

The adrenal gland was not immediately visible upon inspection of the retroperitoneal space cranial to the left kidney, so an incision was made into the large perirenal fat pad by use of grasping forceps and the harmonic scalpel.c Dissection progressed with a combination of the harmonic scalpel and laparoscopic dissecting forceps. Intermittently, a disposable suction-irrigation deviced was used to aspirate small accumulations of hemorrhage or fat in the dissection planes around the gland once it was located. Once dissection of the base of the phrenicoabdominal vein was complete, the vein was ligated by placement of 3 hemoclips dispensed from a laparoscopic clip appliere inserted into the lower left quadrant port. The harmonic scalpel was used to seal and divide the phrenicoabdominal artery. No obvious gross capsular infringement was observed during the dissection.

Once dissected free, the adrenal gland was suspended within the abdomen and the cut thumb of a size 8 surgical glove was inserted through the 10-mm port to act as a specimen retrieval bag. Prior to insertion, the thumb of the glove was manipulated into an inside-out position, allowing the cut end of the thumb to stand open, facilitating specimen placement into the bag.2 After specimen removal, the surgical site was closely inspected for any residual hemorrhage, the site was flushed, and the pneumoperitoneum was purged prior to routine closure of the portal incisions. Total anesthesia time was 165 minutes. Surgical time for the LA was 60 minutes.

The cat recovered from surgery without complications and was discharged from the hospital 4 days after surgery. Histologic examination of the resected left adrenal gland revealed an adrenal cortical adenoma. Histologic examination of the resected right thyroid and parathyroid glands revealed a thyroid adenoma and a parathyroid adenoma. Prednisone with a tapering dosage was prescribed (0.22 mg/kg [0.10 mg/lb], PO, q 24 h for 2 weeks; then 0.15 mg/kg [0.07 mg/lb], PO, q 24 h for 2 weeks; and then 0.15 mg/kg, PO, q 48 h for 2 weeks) to correct any temporary postadrenalectomy hypoadrenocortical state. Serum biochemical panels at 1, 2, 6, 10, 18, and 26 weeks after surgery demonstrated resolution of the hypophosphatemia and hypokalemia. Serum aldosterone concentrations were not measured again after adrenalectomy, but systolic arterial blood pressure measurements at 10 and 18 weeks after adrenalectomy (145 and 120 mm Hg, respectively) demonstrated resolution of the hypertension that had been persistent for 19 months. In addition, follow-up echocardiography at 18 weeks after adrenalectomy showed moderate improvement of the left ventricular hypertrophy following resolution of the systemic hypertension. Subsequent echocardiographic examinations found that the heart disease remained stable at the final cardiac evaluation 3 years after adrenalectomy. Abdominal ultrasonography performed up to 26 months after adrenalectomy revealed no evidence of regrowth of the adrenal mass.

The patient had a history of left-sided ureterolithiasis that was first noticed via ultrasonography 3 months prior to left-sided adrenalectomy. Three ultrasonographic examinations after adrenalectomy showed minimally progressive chronic renal changes in the left kidney without progression in the pyelectasia. However, findings on biochemical analyses remained stable. In addition to chronic renal insufficiency, serum cholesterol concentrations were high 19 months after adrenalectomy (401 mg/dL; reference range, 96 to 248 mg/dL) and serum glucose concentrations were high 39 months after adrenalectomy (509 mg/dL; reference range, 65 to 168 mg/dL); a diagnosis of diabetes mellitus was made.

The patient survived with resolved hyperthyroidism, resolved hyperaldosteronism, resolved hyperadrenocorticism, resolved hyperparathyroidism, and resolved hypertension for 44 months after left adrenalectomy, right thyroidectomy, and right parathyroidectomy. The patient's chronic kidney disease and diabetes mellitus remained stable. Although the patient's cardiac disease remained stable for at least 36 months, 44 months after adrenalectomy, the patient was again evaluated because of an episode of acute collapse. Congestive heart failure was diagnosed via echocardiography, and an aortic thromboembolism was identified via ultrasonography; the patient was therefore euthanized.

Discussion

Hyperaldosteronism in cats can be primary or secondary with principal disease characteristics including hyperaldosteronemia, hypokalemia, and hypertension. Primary hyperaldosteronism in cats was first described by Eger et al3 in 1983. Clinical signs in feline patients relate primarily to hypokalemic polymyopathy and systemic hypertension.4–6 This can often manifest as acute-onset blindness. Since 1983, 34 cats with PHA have been described in the literature.3,7–16 Of the 24 affected animals for which histologic examination results have been published, 12 had unilateral carcinoma, 7 had unilateral adenoma, 2 had bilateral adenomas, and 3 had extensive micronodular adrenal hyperplasia.3,7–15 One case involved tumor thrombi invading the phrenicoabdominal vein only, 3 involved tumor thrombi invading the phrenicoabdominal vein and caudal vena cava, 2 involved metastasis to the lungs, 1 involved metastasis to the liver, and 1 involved concurrent functional endocrine tumors in the pancreas and parathyroid gland.3,9–12,14 Half of cases in cats are carcinomas, and approximately half are adenomas, with only a small minority being described as hyperplasia. In addition, unilateral disease appears to be much more common than bilateral disease.

Both medical management and surgical management have been used in the treatment of PHA in cats. Medical management resolved hypokalemia in some patients, but other patients either required increasing doses of spironolactone to maintain normokalemia or could not achieve normokalemia with medical management alone.3,7,8,13 In addition, hypertension in some patients remained refractory.7,8 Untreated patients survived for 1.5 to 4 months, and medically managed patients survived for 2.5 to 32 months, with most patients euthanized because of renal failure.3,7,8,13 Surgical management of histologically confirmed PHA by unilateral adrenalectomy has been described in 18 feline patients. Of these cats, 6 died within 1 week afterward because of surgical complications, including hemorrhage and sepsis.7,10,11 Of the 12 longer-term survivors, postoperative serum potassium concentrations have been reported in 5 cases.8,9,12–14 Resolution of hypokalemia and associated clinical signs occurred in all 5 patients. When measured, hypertension also resolved in these patients. One of these patients was lost to follow-up at 6 months after adrenalectomy, but the survival times of the other 11 patients ranged from 12 to 20 months.8,9,12–14 Medical management only alleviates clinical signs of PHA in some cases, and it does not address the underlying adrenal cause. Continued growth of an adrenal mass poses a risk to patients because of the potential of bleeding, tumor thrombi formation, or metastasis in cases of adrenal carcinoma.3,9–12 In contrast to medical management, surgical management seems to be curative for PHA because hypokalemia, hypertension, and associated clinical signs resolve without further treatment.7–9,12,14 For these reasons, surgical management is the preferred treatment for cats with unilateral functional adrenal neoplasia when diagnostic imaging has ruled out intravascular invasion and metastatic disease.6 Unfortunately, there are significant complications associated with adrenalectomy in feline patients with PHA.7,10–11 However, if patients survive the immediate postoperative period, the prognosis is generally good.8–9,12–14

Compared with traditional open adrenalectomy for management of PHA in humans, LA is associated with decreased postoperative morbidity, signs of pain, duration of hospitalization, and recovery time.17–19 This has resulted in the adoption of LA as the standard of care for human patients with unilateral PHA.18 It cannot be proven at this time that the advantages of a minimally invasive approach seen in humans would be realized in cats, although studies20–22 in dogs have shown decreases in signs of pain and a more rapid return to normal activity after minimally invasive surgery, compared with open surgery. Although the LA procedure has been described in 7 dogs for management of adrenocortical carcinomas,23 the present report is the first to describe functional adrenal adenoma in a feline patient being managed with LA.

Laparoscopic adrenalectomy is an advanced laparoscopic procedure. Ideally, surgeons should have some laparoscopic experience and be familiar with open adrenalectomy techniques prior to attempting LA. The authors consider certain technical aspects, laparoscopic instrumentation, and specialized equipment beyond the basic endoscopic tower to be crucial in achieving success with these cases and avoidance of a high rate of conversion to open surgery.24 Positioning of the patient in complete lateral recumbency is important to allow other organs to fall ventrally away from the area of gland dissection. In dogs, it has been recommended that a wedge of foam be placed under the epaxial muscles to aid in positioning of dogs undergoing LA.23 A wedge was not used in the cat of the present report, but it might have helped with gravity-induced organ retraction during the procedure. The instrument ports were positioned in a triangulating pattern around the anticipated location of the adrenal gland, with the camera portal located in a subumbilical position.

Localizing the camera portal 2 to 4 cm lateral to the umbilicus in the left flank in dogs has now been adopted by the authors and can give a better angle for visualization of the gland. The enlarged adrenal gland in the cat of the present report was located in the large bed of perirenal fat that is commonly present in cats. Its location was not immediately obvious, and exploration of the fat pad cranial to the cranial pole of the left kidney was necessary. The authors found the use of a 30° telescope very helpful to allow greater visualization of all aspects of the mass during dissection. This is possible because of the angled tip of the telescope, which provides a visual field that is offset by 30° and allows tissue planes not directly in front of the telescope to be viewed by external rotation of the lightpost.

The harmonic scalpel is an ultrasonic vessel sealer that is indicated for sealing of blood vessels up to 5 mm in diameter.25 It allows effective sealing of the many arteries and veins within the dissection planes around the mass and prevents small nuisance bleeding that can impair visualization and which is more difficult to clear when a minimally invasive approach is used. The tip of the harmonic scalpel is also an excellent dissector because the narrow and slightly curved tip design allows easy insertion into dissection planes around the mass. The authors have also used bipolar vessel-sealing devices for LA in dogs and found them to be equally effective for this application. Both these devices could probably be used to seal and divide even the largest vessels encountered during an LA procedure, which are typically the phrenicoabdominal vein and artery. For the cat of the present report, laparoscopic clips were used on the vein only. The choice of clips was the personal preference of the surgeon, and it is unknown whether any particular ligation method will prove superior to any other for vessel ligation. The use of a disposable suction-irrigation device is also helpful for LA. The suction-irrigation wand can be used as a dissection instrument for aspirating small amounts of hemorrhage and fat from tissue planes around the tumor. This improves visualization and helps to minimize instrument changes.

Intravascular invasion occurs in approximately 25% of adrenal tumors in dogs and has been seen in 4 of 21 cases of histologically confirmed functional adrenal neoplasia in cats.9,11,12,26 At this time, in agreement with the conclusions of Jiménez Peléez et al,23 intravascular invasion should be considered a contraindication for LA, so ruling out invasion before surgery is of paramount importance. Although no information specific to cats is available, ultrasonography has been shown to have a sensitivity of 80% and a specificity of 90% for detection of tumor thrombi in dogs.26 Computed tomography has been shown to have a sensitivity of 92% and a specificity of 100% for detection of tumor thrombi in dogs.27 Computed tomography may therefore have some advantage over ultrasonography in preoperative detection of intravascular invasion and is currently the diagnostic imaging tool of choice in the authors’ institution when case selection for LA is being considered. Although a CT scan was planned in the cat of the present report 2 weeks prior to surgery, it was not performed because of anesthetic concerns about the patient's severe hypokalemia (2.3 mmol/L; reference range, 3.5 to 4.8 mmol/L). Instead, ultrasonography was performed to rule out intravascular invasion of the tumor. It should be noted that for the initial diagnosis of PHA, abnormal adrenal hormone secretion may not be accompanied by morphological changes recognizable with even the most precise methods, so absence of lesions on diagnostic imaging should not rule out the possibility of PHA caused by micronodular hyperplasia.28

In conclusion, LA may be a plausible method for the treatment of unilateral functional adrenal neoplasia in feline patients when diagnostic imaging has ruled out intravascular invasion and metastatic disease. Laparoscopic adrenalectomy may help to reduce morbidity after surgery, although larger studies comparing open surgery with LA will be required to support this hypothesis. The patient of the present report not only had adrenal neoplasia but also neoplasia of the thyroid and parathyroid glands. In a feline patient with a hyperfunctioning endocrine gland, other endocrine glands should be screened for the presence of additional endocrine neoplasms.

ABBREVIATIONS

LA

Laparoscopic adrenalectomy

PHA

Primary hyperaldosteronism

a.

Hopkins 5 mm 30° laparoscope, Karl Storz Veterinary Endoscopy. Goleta, Calif.

b.

Endotip, Karl Storz Veterinary Endoscopy, Goleta, Calif.

c.

Harmonic ACE, Ethicon Endo-Surgery Inc, Cincinnati, Ohio.

d.

Flovac, Conmed Endosurgery Inc, Utica, NY.

e.

M/L-10, Microline Pentax, Beverly, Mass.

References

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  • Figure 1—

    Photograph showing port placement for LA in a 9-year-old castrated male domestic shorthair cat with concurrent hyperparathyroidism and hyperadrenocorticism. A 3-portal technique was used with the camera portal located in a subumbilical position. Instrument ports are established in the left cranial and caudal abdominal quadrants.

  • 1 Mayhew PD, Brown DC. Comparison of three techniques for ovarian pedicle hemostasis during laparoscopic-assisted ovariohysterectomy. Vet Surg 2007; 36:541547.

    • Search Google Scholar
    • Export Citation
  • 2 Gett R & Johnson M. Appendix retrieval after laparoscopic appendectomy: a safe and inexpensive technique (lett). Surg Laparosc Endosc Percutan Tech 2006; 5:378.

    • Search Google Scholar
    • Export Citation
  • 3 Eger CE, Robinson WF, Huxtable CR. Primary aldosteronism (Conn's syndrome) in a cat; a case report and review of comparative aspects. J Small Anim Pract 1983; 24:293307.

    • Search Google Scholar
    • Export Citation
  • 4 Dow SW, LeCouteur RA, Fettman MJ, et al. Potassium depletion in cats: hypokalemic polymyopathy. J Am Vet Med Assoc 1987; 191:15631568.

    • Search Google Scholar
    • Export Citation
  • 5 Reusch CE, Schellenberg S & Wenger M. Endocrine hypertension in small animals. Vet Clin North Am Small Anim Pract 2010; 40:335352.

  • 6 Schulman RL. Feline primary hyperaldosteronism, a literature review. Vet Clin North Am Small Anim Pract 2010; 40:353359.

  • 7 Ash RA, Harvey AM & Tasker S. Primary hyperaldosteronism in the cat: a series of 13 cases. J Feline Med Surg 2005; 7:173182.

  • 8 Flood SM, Randolph JF, Gelzer AR, et al. Primary hyperaldosteronism in two cats. J Am Anim Hosp Assoc 1999; 35:411416.

  • 9 Rose SA, Kyles AE, Labelle P, et al. Adrenalectomy and caval thrombectomy in a cat with primary hyperaldosteronism. J Am Anim Hosp Assoc 2007; 43:209214.

    • Search Google Scholar
    • Export Citation
  • 10 DeClue AE, Breshears LA, Pardo ID, et al. Hyperaldosteronism and hyperprogesteronism in a cat with an adrenal cortical carcinoma. J Vet Intern Med 2005; 19:355358.

    • Search Google Scholar
    • Export Citation
  • 11 Rijnberk A, Voorhout G, Kooistra HS, et al. Hyperaldosteronism in a cat with metastasized adrenocortical tumour. Vet Q 2001; 23:3843.

    • Search Google Scholar
    • Export Citation
  • 12 MacKay AD, Holt PE, Sparkes AH. Successful surgical treatment of a cat with primary hyperaldosteronism. J Feline Med Surg 1999; 1:117122.

    • Search Google Scholar
    • Export Citation
  • 13 Javadi S, Djajadiningrat-Laanen SC, Kooistra HS, et al. Primary hyperaldosteronism, a mediator of progressive renal disease in cats. Domest Anim Endocrinol 2005; 28:85104.

    • Search Google Scholar
    • Export Citation
  • 14 Reimer SB, Pelosi A, Frank JD, et al. Multiple endocrine neoplasia type 1 in a cat. J Am Vet Med Assoc 2005; 227:101104.

  • 15 Renschler JS, Dean GA. What is your diagnosis? Abdominal mass aspirate in a cat with an increased Na:K ratio. Vet Clin Pathol 2009; 38:6972.

    • Search Google Scholar
    • Export Citation
  • 16 Moore LE, Biller DS, Smith TA. Use of abdominal ultrasonography in the diagnosis of primary hyperaldosteronism in a cat. J Am Vet Med Assoc 2000; 217:213215.

    • Search Google Scholar
    • Export Citation
  • 17 Duncan JL, Fuhrman GM, Bolton JS, et al. Laparoscopic adrenalectomy is superior to an open approach to treat hyperaldosteronism. Am Surg 2000; 66:932936.

    • Search Google Scholar
    • Export Citation
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