Prognostic Value of Cardiac Troponin I and L‐Lactate in Blood of Dairy Cows Affected by Downer Cow Syndrome

BACKGROUND The downer cow syndrome (DCS) is a challenging health issue in the dairy industry. No cow-side test is available to provide an accurate prognosis for DCS cases in farm settings. HYPOTHESIS/OBJECTIVES Local or systemic hypoperfusion and myocardial lesions lead to an increase in blood concentration of biomarkers cardiac troponin I (cTnI) and L-lactate. The objective was to determine the prognostic values of these biomarkers assessed cow-sides in addition to clinical examinations in prognostication of a negative outcome (NO: death or euthanasia within 7 days). ANIMALS 218 client-owned dairy cows affected by DCS. METHODS In a prospective study, animals were monitored for 60 days after inclusion of each cow. Blood cTnI and L-lactate concentrations were measured on the day of inclusion. The prognostic accuracy of both biomarkers and physical examination variables was estimated to predict NO. A mixed multivariable logistic regression model was used for data analysis. RESULTS Prevalence of NO in this study was 63% on day 7. Troponin concentrations greater than 0.7 ng/mL had sensitivity and specificity of 54.1% (95% CI: 45.3-62.7%) and 78.4% (95% CI: 67.3-87.1%), respectively, for predicting NO. Blood L-lactate was not associated with the outcome. The multivariable model revealed that heart rate >100 bpm (OR; 95% CI: 3.7; 1.3-10.2) and cTnI > 0.7 ng/mL (OR; 95% CI: 5.5; 2.1-14.6) were associated with the risk of NO. CONCLUSIONS AND CLINICAL IMPORTANCE Hypertroponinemia and tachycardia were associated with reduced survival in DCS cases. The use of cow-side blood cTnI concentrations and heart rate could help to rapidly identify cows in farm setting that have poor chances of recovery and would benefit from a more aggressive treatment or euthanasia.