Norvasc can create numerous side effects in animals. Quite frequently, a missed dose can lead to a spontaneous increase in blood pressure, ultimately resulting in blindness, kidney damage, seizures, or collapse. Some other side effects of the medicine include drowsiness, dizziness, loss of appetite, weight loss, collapse, or a rapid or slow heart rate. One of the most important side effects of the drug is low blood pressure or ‘Hypotension’ caused by increased dilation of arteries, resulting in depression, weakness or even fainting.