Can the age-old practices of animal selection and breeding and the more recent biotechnological interventions on animals, far more intrusive and systematic than any present form of human enhancement, enlighten us as to the future of enhancement practices? This book explores issues raised by past and present practices of animal enhancement in terms of their means and their goals, clarifies conceptual issues and identifies lessons that can be learned about enhancement practices, as they concern both animals and humans. The extreme ambiguity of the claim that animals are being enhanced, the driving goals and strategies of third-party interests, but also the similarity of the substances and techniques used on humans and animals, suggest that human enhancement practices may be just as tainted by equivocal goals and strategies as equivalent practices with animals.