The Vcheck TnI biomarker is an in vitro diagnostic test kit for the in-clinic quantitative measurement of cardiac troponin I concentration in feline serum. Troponin consists of 3 subunits (troponin I, T, and C) which together function as the molecular switch of cardiomyocyte contraction. Among them, cardiac Troponin I (TnI) is a sensitive and specific circulating marker of cardiac injury for felines. Cardiac injury causes the release of TnI into the circulation, where its concentration is correlated to the severity of the damage. Hypertrophic cardiomyopathy (HCM) is the most common heart disease and one of the 10 most common causes of death in felines. Measuring TnI concentrations can be useful in detecting subclinical HCM and predicting cardiac death in felines with HCM.