Usefulness of Measuring QT Interval in Beagle Dogs with Chest Lead

ECGs by standard limb leads and the chest lead (CV5RL lead) were simultaneously recorded in healthy 14 male (10-11 months old, weighing 7.42-10.70 kg) and 12 female (10-11 months old, weighing 5.54-7.40 kg) beagle dogs in the hanging position in slings without anesthesia. QT interval and the amplitude of T wave analyzed by the chest lead were compared with those from lead II. We concluded as follows: 1. The CV5RL lead gives constantly positive well defined T wave, and the amplitudes of T waves recorded by the lead were 1.7-7.5 folds larger than those recorded from lead II, whereas the patterns of T waves recorded from lead II were variable and were positive, negative, biphasic (negative followed by positive) and bifid (positive followed by positive). 2. The mean QT interval analyzed by the CV5RL lead was 4 msec (corresponded to 2% of the mean QT interval by lead II) longer than that analyzed by lead II. The 4 msec was considered to be incidental caused by the difference of the ECG leads. 3. Simultaneous ECG recording by standard limb lead (6 leads) and the CV5RL lead is not complicated, and the evaluation of QT interval by the CV5RL lead may be useful for the comparison of the intervals in same animal or other animals.