1985 Volume 18 Issue 18 Pages 43-49
Electrocardiography during the first 90 days of life was studied in 17 beagle puppies. They were from parents without a history of heart disease. Electrocardiograms were recorded by standard limb leads (I, II, III) and augmented unipolar limb leads (aVR, aVL, aVF). Two of the 17 the puppies were excluded from the results because of the findings markedly different from those of the other puppies.
1) Heart rate increased gradually to around 200 by the 30-40th day and then decreased to around 150 on the 90th day.
2) The variation of P wave voltage was not recorded until the 90th day, but T wave voltage tended to increase gradually until the 40th day of life, and then to decrease until the 90th day.
3) The R/S ratio in the II lead increased from less than 1.0 at birth to more than 2.0 on the 25th day.
4) QRS complex in each leads indicated the same wave pattern as in adult dogs around the second week of life.
5) The QRS modal axis changed from a leftward and cranial (+133.5°-160.8°, av.-136.5°) at birth to a rightward and ventral orientation (+19.8°-+101.4°, av.+52.9°) on the 90th day.
