Changes in the heart beat of puppies in the first twelve weeks of life

In 37 healthy pups and seven pups with congenital pulmonic stenosis ECG were recorded and the heart rate determined. Between the first week of life in healthy pups (mean = 230/min) and the twelfth week of life the heart rate in both groups at six weeks was 195/min and 180/min. At the end of the investigation the averaged heart rate was 167/min or 166/min respectively. In single weeks during the investigation a slightly increased heart rate occurred in a few dogs between the fourth and sixth week of life owing to an increased restlessness during this time span. The heart rate of newborn pups at the first day (mean = 215/min) was a little lower than the average in the first week of life.