Myocardial injury associated with naturally occurring clinical bovine anaplasmosis: evaluation of novel cardiac biomarkers.

Severe anaemia and tissue hypoxia in bovine anaplasmosis may result in myocardial injury; however, the extent of cardiac involvement has not been comprehensively investigated using circulating cardiac biomarkers. The present study aimed to evaluate myocardial injury in cattle naturally infected with Anaplasma spp. and to determine the most reliable cardiac biomarkers for detecting cardiac damage. A case-control study was conducted in 24 Simmental calves, including 12 clinically affected calves and 12 healthy controls. Only clinically affected animals were included in the infected group, whereas quantitative real-time PCR (qPCR) positive but clinically normal cattle were excluded. Diagnosis was based on clinical examination, microscopic blood smear evaluation, and qPCR. Serum cTnI, CK-MB, AST, and LDH were measured using commercial enzyme kits, whereas H-FABP and NT-proBNP concentrations were determined using bovine-specific ELISA kits. Mean serum H-FABP (0.64 vs. 0.43 ng/mL; P < 0.001) and NT-proBNP (0.36 vs. 0.21 ng/mL; P < 0.001) concentrations, as well as median cTnI levels (0.11 vs. 0.06 ng/mL; P = 0.003), were significantly higher in cattle with anaplasmosis than in healthy controls. Haematocrit showed moderate negative correlations with H-FABP (r = -0.413, P = 0.045) and NT-proBNP (r = -0.617, P = 0.001). Heart rate showed strong positive correlations with H-FABP (r = 0.803, P < 0.001) and NT-proBNP (r = 0.732, P < 0.001), and a moderate positive correlation with cTnI (r = 0.537, P = 0.007). ROC analysis identified H-FABP as the best-performing biomarker (AUC = 1.000), followed by NT-proBNP (AUC = 0.903) and cTnI (AUC = 0.854). In conclusion, naturally occurring bovine anaplasmosis is associated with significant myocardial injury likely related to anaemia-induced hypoxia and compensatory tachycardia. Among the evaluated biomarkers, H-FABP demonstrated the highest diagnostic performance and may facilitate earlier recognition of cardiac involvement in affected cattle.