Doctors have a way to protect pets from diseases: vaccines. Here’s why your puppy should get them. What is a vaccine? The history of vaccines starts with an epidemic of smallpox, which killed millions of people. In 1796, a physician named Edward Jenner noticed that the milk maids, who were routinely exposed to cowpox, did not get sick with small-pox. He wondered whether their exposure to cowpox protected them, and the idea of vaccination was born. A vaccine exposes the immune system to inactive or incomplete disease-causing agents to train the immune system to quickly and effectively respond when exposed to the real thing. Why do we vaccinate puppies? Since…