Abstract: Background-Cardiac troponin I ([cTnI]) is a biomarker for myocardial insult, and reference intervals have been established for adult horses. In neonatal foals, [cTnI], arrhythmia burden and echocardiographic variables are not well characterized.
Hypothesis/Objectives- To establish [cTnI] reference intervals, arrhythmia burden, and echocardiographic variables in healthy foals.
Animals- Five University owned foals.
Methods- Blood was collected at 0, 6, 12, 18, 24, 48, 72, and 120 hrs of age, and stored at -80C. Complete echocardiograms were performed at 24 hrs, 5 days, and 21 days. An ECG was recorded for 24 hrs, beginning at 12 hrs of age. Plasma [cTnI] was measured (iSTAT-1, Abbott Laboratories).
Results- Four of five foals had [cTnI] outside the reference interval for adult horses ( < 0.06 ng/mL). The [cTnI] peaked at 6 hrs with a mean (standard deviation) of 0.16 (0.09); decreased at 12, 18 and 24 hrs: 0.11 (0.07), 0.08 (0.11), and 0.06 (0.06) respectively. An ECG was recorded in 4/5 foals. Analysis revealed supraventricular and ventricular arrhythmias. Echocardiographically, foals had prominent right hearts, changes in tissue Doppler variables compared to adults, pulmonary artery flow acceleration and turbulence, and the ductus arteriosus remained open on day 5 in all foals and was closed at 21 days.
Conclusions and Clinical Importance- Arrhythmia burden and [cTnI] in neonatal foals is higher compared to adults. The ductus arteriosus remained open in all foals on day 5 indicating that further investigation to characterize the timing of ductus closure is needed. Five additional foals will be investigated in spring 2025.
