Electrocardiogram, hemodynamics, and core body temperatures of the normal freely moving laboratory beagle dog by remote radiotelemetry.

INTRODUCTION: The objectives of this study were to provide baseline normative values for circadian changes in the time-series data collected over the course of a normal day in laboratory-housed dogs and to assess the relative efficiency of standard correction formulas to correct for the variations in QT intervals and heart rate functions.
METHODS: One hundred and twenty-three beagle dogs (65 M, 58 F) were equipped with radiotelemetry transmitters and continuously monitored, while freely moving in their home cages. Electrocardiograms (ECGs), hemodynamic parameters (diastolic, systolic, and mean arterial pressures) as well as core body temperatures were recorded for 22 h. RESULTS AND DISCUSSION: Blood pressures and core body temperatures demonstrated only very slight variations in their respective values over the 22-h monitoring period. ECGs were measured by a computerized waveform analysis program and quantitative elements reported as RR, PR, QRS, and QT intervals. Little circadian rhythmicity was demonstrated in the ECG intervals. Standard study-specific correction formulas appeared to satisfactorily normalize (i.e., compensate for) the relationship between heart rate and QT intervals in these beagle dogs but elevated the values of the QTc as compared to the uncorrected QT intervals. In sharp contrast, a subject-specific correction method based on analysis of covariance produced a more linear function between heart rates and QT intervals and, more importantly, provided QTc values within the normal range of actual, recorded QT interval data.