Hyperaldosteronism case report: Reviving a senior cat's verve

Mar 01, 2012

A 13-year-old 10.3-lb (4.68-kg) spayed female domestic shorthaired cat was presented to the VCA West Los Angeles Animal Hospital for progressive and unresolving lethargy over the course of two to three days and one episode of vomiting. The owner reported that the cat recently showed an inability or unwillingness to jump onto elevated surfaces and described signs consistent with a plantigrade hindlimb stance that was episodic in nature. The cat was otherwise healthy with no preexisting conditions and was receiving no medications. It lived in a household as the sole pet and was indoor-only, and there was no known exposure to or ingestion of toxins.

Physical examination

On physical examination, the cat was quiet, alert, and responsive, with a body condition score of 5/9. The cat's vital signs were normal (temperature = 101.4 F [38.6 C]; heart rate = 140 beats/min; respiratory rate = 30 breaths/min), and the cat appeared to be mildly dehydrated with tacky mucous membranes. A grade II/VI left systolic parasternal heart murmur was detected on thoracic auscultation. Musculoskeletal examination revealed cervical ventroflexion and generalized weakness.

Clinicopathologic tests

Table A
In-house and laboratory diagnostics were performed, and selected results are shown in Table A. A thoracic radiographic examination revealed mild cardiomegaly with normal pulmonary parenchyma and vasculature. After the initial in-house blood analysis and thoracic radiographic examination, the differential diagnoses included hyperthyroidism, hypokalemic nephropathy, pyelonephritis, primary hyperaldosteronism, and cardiomyopathy.

Initial treatment

Table B
The cat was hospitalized and initially started on lactated Ringer's solution with 40 mEq/L of potassium chloride at a maintenance rate of 50 ml/kg/day. The next morning, samples were collected for outside evaluation, and the results are presented in Table B. Potassium concentrations were monitored every six hours, and the potassium chloride supplementation in intravenous fluid was adjusted accordingly. Oral potassium gluconate supplementation (2 mEq every eight hours) and amoxicillin trihydrate-clavulanate potassium (13.75 mg/kg every 12 hours) were instituted.

The cat's blood pressure was measured by using a Doppler monitor every six hours for 24 hours. A mean systolic value, calculated from at least three consecutive measurements, was reported. Over 24 hours, the cat's blood pressure ranged from a mean systolic of 180 to 195 mm Hg. Retinal examination revealed bilateral tortuous vessels and mild focal hemorrhage of the right eye. The cat was started on amlodipine (0.625 mg orally every 24 hours).

After analysis of the commercial laboratory data (Table B), hyperthyroidism appeared to be unlikely, so abdominal ultrasonography was recommended in addition to measurement of plasma aldosterone concentration.