Introduction/ObjectivesThis study aimed to evaluate circulating amino-terminal pro-B-type natriuretic peptide (NT-proBNP), amino-terminal pro-A-type natriuretic peptide (NT-proANP), and cardiac troponin I (cTnI) concentrations in dogs with precapillary pulmonary hypertension (Pre-PH) and control dogs with respiratory clinical signs but no Pre-PH. AnimalsTwenty-sixdogs (17 affected and 9 controls) were involved in the study. Materials and MethodsThis was a substudy of a large prospective single-center observational study. Dogs underwent blood sample collection, physical examination, and echocardiographic evaluation. Pre-PH was diagnosed when a calculated right ventricular-to right atrial pressure gradient (RV:RA PG) measuring ≥40 mm Hg was identified echocardiographically, barring pulmonic stenosis or right ventricular outflow tract obstruction, and in case of left-sided cardiac disease. ResultsTwo, nine, and six dogs had mild, moderate, and severe Pre-PH, respectively. Plasma concentrations of NT-proBNP, NT-proANP, and cTnI were significantly higher in the affected group than in the control group (P=0.020, P=0.009, P=0.011, respectively). There was a positive correlation between RV:RA PG and NT-proBNP (r = 0.52), NT-proANP (r = 0.54), and cTnI (r = 0.67) concentrations. Study LimitationsFollowing were the limitations: limited sample size and missing data points. The diagnosis of Pre-PH was obtained from Doppler echocardiographic RV:RA PG. The underlying disease process causing Pre-PH was not evaluated histopathologically. ConclusionsCirculating cardiac biomarker concentrations are increased in dogs with Pre-PH and there is a positive correlation between RV:RA PG and NT-proBNP, NT-proANP, and cTnI concentrations. Based on those results, Pre-PH should be included in the differential diagnosis list of elevated cardiac biomarker concentrations in dogs with respiratory signs.