Abstract
We investigated 613 cases of ECG in beagle dogs at 6 to 20 months of age, which are the animals usually employed in general toxicity studies. T wave patterns in the present examples were examined and discussed from the point of toxicity evaluation. Incidence was 52.3, 34.2, and 13.5% for the positive, negative, and biphasic waves, respectively, with the incidence of the positive wave exceeding 50% in animals at 6 months of age. However, the incidence of positive waves decreased to 33.3–36.7% and that of negative waves increased to 50.0–60.0% at the age of 7–10 months, and negative waves showed a tendency to further increase gradually thereafter. T wave pattern also changes in accordance with posture or induction method employed, and therefore it is essential for T wave data to be evaluated in conjunction with other data such as clinical chemistry.
