This book would not have been written without the encouragement and help which others have given me in developing an interest in equine cardiology. This interest evolved during my years in practice and at the University of Bristol School of Veterinary Science. The opportunity to indulge my special interest came through a Horserace Betting Levy Board research training scholarship and was encouraged by referrals from vets in practice and from the stimulation of teaching students. Many colleagues have contributed to my learning, but I owe particular thanks to Dr Christine Gibbs and Dr Paul Wotton. I would also like to pay tribute to Dr Jim Holmes, who was influential in the development of equine cardiology. I was fortunate enough to work with Dr Holmes during the first year of my PhD. I would also like to acknowledge the contribution to the subject made in recent years by Dr Virginia Reef, who has been a guiding light to amny cardiologists in the reading list. I am extremely grateful to Paul Wotton and Jill Richardson who read the book and made valuable comments. I would never have completed the book without the encouragement and understanding of my wife Jo.