The amount that he consumed was quite low, about a quarter of the low end dose that is given to dogs to assist in reducing blood pressure. Your concern about the medication having an affect is low, my concern would be how much of the pill bottle he has consumed and whether it is going to pass. Monitor for signs of weakness, excessive tiredness, vomiting, or depression. If these do present I would have him seen by a veterinarian.
Norvasc and blood pressure in dogs
Norvasc is a drug that is given to cats and dogs. Below will explain the side effects. Please let me know if you need further help.