Abstract
Background:
Plasma N-terminal pro-atrial natriuretic peptide (NT-proANP) and plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentrations may be affected by the hydration status.
Aim:
This study aimed to evaluate the effect of dehydration on plasma NT-proANP and NT-proBNP concentrations in healthy dogs.
Methods:
This prospective study included five clinically healthy dogs. Furosemide was administered intravenously at 2–4 mg/kg every 1–2 h until completion of the dehydration model. The dehydration model was considered complete when weight loss was ≥5% and findings of dehydration on physical examination were observed. Plasma NT-proANP and NT-proBNP concentrations were compared at three time points: before the dehydration model was created (point 1), at the completion of the dehydration model (point 2), and when dehydration was judged to have improved (point 3). Association between plasma NT-proANP and NT-proBNP concentrations, and each clinical variable (physical examination, blood pressure, blood chemistry, blood gases, and echocardiography) was assessed using linear regression analysis.
Results:
Plasma NT-proANP concentration decreased significantly from point 2 to point 1 (p < 0.05), whereas plasma NT-proBNP concentration showed a decreasing trend but did not differ significantly between points 1 and 2. Plasma NT-proANP concentration correlated significantly with body weight (R2 = 0.178) and plasma NT-proBNP concentration (R2 = 0.284) (p < 0.05, respectively), and plasma NT-proBNP concentration correlated significantly with electrolytes (sodium, R2 = 0.439; potassium, R2 = 0.444; chloride, R2 = 0.419), and echocardiographic parameters (diastolic left ventricular internal diameter [LVIDd], R2 = 0.519; weight-standardised LVIDd, R2 = 0.535) (p < 0.01, respectively).
Conclusion:
The plasma NT-proANP concentrations decreased with dehydration. However, the plasma NT-proBNP concentration did not change with mild dehydration and reflected left ventricular morphology.

Key words: Cardiac biomarkers, Dehydration, Dogs, Fluid volume, N-terminal pro-atrial natriuretic peptide