I see a lot of dogs in my typical workday. Some sick, some healthy, many somewhere in between. I sometimes remember some details about them after their appointments, but there are a few dogs that are forever vividly etched in my memory. This is the case with Lucy, a 4 month old black Labrador mix adopted from a local rescue group. Lucy was my 9:15 appointment on an early fall Saturday morning, over eight years ago. It was a beautiful day, and I was looking forward to meeting a friend for lunch and then spending some time with my own dogs. Lucy had been with her owners a few weeks, and was a typical happy, active puppy. She had received her first vaccination (DAPP) four weeks ago while with her foster family. My physical examination revealed no abnormalities - she appeared completely healthy. So I administered her second DAPP vaccination, which happened to be exactly the same brand and formulation she had received a month ago. Before I could withdraw the needle from her skin, it was apparent that something was very wrong. Lucy stiffened, and then collapsed. I immediately began treatment for this vaccine reaction, and she responded initially. She had her first seizure half an hour later. Over the course of the morning, her seizures progressed, and she stopped responding to the intravenous fluids and drugs we administered. She died at 2:16 PM, just over five hours after she bounced into the hospital, a bright, happy puppy with a tennis ball in her mouth. My purpose in writing this book is to provide a straightforward explanation of what a vaccine is, how it works, and which are (and are not) needed for most dogs. This information is what I want to share with every new puppy owner at his or her first office call (and now that it is in book form I can!). As such, it is intended to be an understandable yet not dumbed down explanation of this important medical procedure for every concerned dog owner. You will notice scientific references sprinkled throughout the chapters, as well as in the References section. More technical information is available at the book website, www.VaccinesExplained.com for those interested. My basic vaccination schedule and Best Practices for vaccinating are also included. I sincerely hope this guide aids you in making informed vaccine choices for your dog.