Clinical findings, treatment, and outcomes in cats with naturally occurring hypoadrenocorticism: 41 cases

Background: Hypoadrenocorticism in cats is uncommonly reported. Most reports consist of cats with hyponatremia, hyperkalemia, or both.

Hypothesis/objectives: To describe clinical findings, treatment response, and outcome in cats diagnosed with hypoadrenocorticism, including cats with abnormal and normal serum sodium and potassium concentrations.

Animals: Forty-one cats with hypoadrenocorticism; 36 with and 5 without abnormal serum sodium and potassium concentrations.

Methods: Multicenter retrospective observational study. Data for the entire cohort were assessed using descriptive statistics and differences between cats with and without abnormal serum sodium and potassium concentrations were evaluated.

Results: Median age was 5.7 years (range, 0.2-13.8). Twenty-three (56%) cats were male and 18 (44%) were female. Cats with hyponatremia, hyperkalemia, or both were less likely to have a history of vomiting (P = .01) but more likely to be hypothermic (P = .03), dehydrated (P = .04) or weak (P = .04) on examination, compared with nonhyponatremic and nonhyperkalemic cats. Frequency of hypercalcemia was 31.7%. Exocrine pancreatic insufficiency (EPI) was diagnosed in 4/7 cats tested; all 4 had concurrent cobalamin deficiency. Thirty-five (85.4%) cats survived to discharge. In 2 cats, hypoadrenocorticism occurred secondary to lymphoma. Median survival time (MST) for all-cause mortality was 2035 days (95% confidence interval [CI], 294-4380 days); MST for disease-specific mortality was not reached.

Conclusions and clinical importance: Approximately one-third of cats with hypoadrenocorticism had hypercalcemia. In some cases, hyponatremia and hyperkalemia were not observed. Cats with nonneoplastic associated hypoadrenocorticism that survive initial hospitalization can have a favorable long-term prognosis. Testing for EPI may be warranted in cats with hypoadrenocorticism.