Since the drugs for blood pressure reduction in veterinary medicine are used in cases of prescribing heart stimulant's drugs and this matter has not been investigated clearly, therefore we determined to do some research in this matter although they might be primary research to provide an outline for future studies and at the same time we took the opportunity to consider the effects of two or three times doses. The drug used in this test is verapamil hydrochloride which is from the group of IV calcium canals' blockades that was used in ten dogs veins and for the statistical consideration, one way ANOVA method and SPSS 9.01 software were used. Taking into consideration the give statistics of electrocardiography in healthy animals, the effects of calcium canals' blockades on SA and AV nodes were observed. Despite of bradycardia case in all animals, an increase in number of heartbeats was seen and this case with the mentioned reasons, could happen as a result of the stimulating vasomotor as the blood pressure reduction occurs because of a decrease in blood vessels' resistance. Because of stimulation in the receivers of carotid and aortic arch, vasomotor center is stimulated and at last cause the protection of main qualities of heart. The proof of this is the unchangeability of PR Int., Dur QRS, and Amp R in which heart will react to the verapamil's effects and it appears that with the existing inputs. Used doses in this study are not completely toxic doses and the toxic effects of this drug happen with the higher doses. Therefore a dose equal to three times of verapamil can be at marginal safety of the drug. Finally the existing cardiogram's changes indicate the changes in heart chronotrope's cases that probably are existed because of controllable effects of drug on heart's muscular contraction power.