Echocardiographic and biomarker evidence of plasma volume expansion after short‐term steroids administered orally in cats

BACKGROUND: Steroids administered PO and intramuscularly are associated with development of congestive heart failure in cats without prior signs of heart disease, but criteria to identify cats at increased risk for steroid‐induced heart failure are not established. HYPOTHESIS: Cats administered steroids PO for 5 to 7 days will develop increased N terminal pro‐B‐type natriuretic peptide (NT‐proBNP) concentration and heart size. ANIMALS: Ten client‐owned cats. METHODS: Observational cohort study. Cats intended to initiate at least a 5‐day course of steroids administered PO were consecutively recruited. RESULTS: Steroids administered PO to cats are not associated with differences in absolute concentration of NT‐proBNP (baseline: 49 pmol/L [range, 24‐1013]; after steroids: 85 pmol/L [range, 46‐1367]; P = .23), blood pressure (baseline: 145 mm Hg [range, 116‐163]; after steroids: 145 mm Hg [range, 115‐230]; P = .94), nor blood glucose concentration (baseline: 125 mg/dL [range, 92‐254]; after steroids: 144 mg/dL [range, 114‐307]; P = .43), but are associated with increased median left atrial dimension (baseline: 1.26 cm [range, 0.96‐2.03; after steroids: 1.38 [range, 1.03‐2.20]; P = .02) and mean left ventricular internal diameter (baseline: 1.55 cm [standard deviation—SD, 0.28; after steroids: 1.72 cm [SD, 0.28]; P = .03). Six of 10 (60%) cats had a percentile change in NT‐proBNP >60% after steroids, and 3 of 8 (38%) cats with baseline BNP <100 pmol/L had an NT‐proBNP >100 pmol/L after steroids. CONCLUSIONS AND CLINICAL IMPORTANCE: Increased heart size and percentage change in individual NT‐proBNP concentration suggests plasma volume expansion secondary to steroids administered PO in cats. A serial assessment of an individual cat's change in NT‐proBNP might be clinically useful for judging risk for volume expansion.