Electrocardiographic findings in 130 hospitalized neonatal calves with diarrhea and associated potassium balance disorders

Background Hyperkalemia in neonatal diarrheic calves can potentially result in serious cardiac conduction abnormalities and arrhythmias. Objectives To document electrocardiographic (ECG) findings and the sequence of ECG changes that are associated with increasing plasma potassium concentrations (cK+) in a large population of neonatal diarrheic calves. Animals One hundred and thirty neonatal diarrheic calves (age ≤21 days). Methods Prospective observational study involving calves admitted to a veterinary teaching hospital. Results Hyperkalemic calves (cK+: 5.8‐10.2, blood pH: 6.55‐7.47) had significantly (P 6.5 mmol/L, S wave amplitude voltage decreased when cK+ >7.4 mmol/L, QRS duration increased when cK+ >7.8 mmol/L, J point amplitude increased when cK+ >7.9 mmol/L, and ST segment angle increased when cK+ >9.1 mmol/L. P wave amplitude was characterized by a second common break point at cK+ = 8.2 mmol/L, above which value the amplitude was 0. Conclusions and Clinical Importance Hyperkalemia in neonatal diarrheic calves is associated with serious cardiac conduction abnormalities. In addition to increased S and T wave amplitude voltages, alterations of P and Ta wave amplitudes are early signs of hyperkalemia, which is consistent with the known sensitivity of atrial myocytes to increased cK+.