The determination of when, how, how often and with whom an animal breeds is moving rapidly away from evolutionary pressures and towards human purposes: these include the breeding of around 50 billion mammals and birds for food production annually, the breeding of pedigree dogs and cats, racing dogs and horses, specialised laboratory animal strains and the use of reproductive science to conserve endangered species or breeds and to limit unwanted populations of pests and non-native species. But the ethics and sustainability of this takeover of animals' reproductive lives have been insufficiently examined by either professionals or the public. This book discusses the methods, the motivations and the consequences of human intervention in animal breeding in terms of animal health, behaviour and well-being. It explores where we are now and the choices ahead, and looks to a future where we have more respect for animals as sentient beings and where we could loosen the reins of reproductive control.