3. Dogs and the Cardiac Pacemaker
Dogs played a pivotal role in the invention of the cardiac pacemaker. Early researchers experimented with electrically stimulating canine hearts to understand how to control abnormal rhythms. Their discoveries led to the first implantable pacemakers, devices that could reliably regulate heartbeats in humans suffering from arrhythmias. Today, millions depend on this technology for a normal, healthy life—a direct legacy of those initial studies in dogs. More from the American Heart Association