For many years, scientists within human and animal science have extensively studied the philosophy of medicine, but never have both sides communicated with each other on the concepts of health, quality of life and welfare. This book aims to help clarify the difficult but central notions of health and welfare by comparing the human and animal variants of these concepts. Split into three parts, this book starts by presenting a background of some of the major theories of human health and welfare, among these are bio-statistical theory, classical theories such as Aristotle and Bentham, as well as objectivist and subjectivist contemporary theories. This is followed by a detailed discussion of theories on animal welfare and health; these include coping, feeling and preference theories. The final part of the book tests a comprehensive conceptual framework of a holistic kind, which focuses on the individual's ability to achieve their vital goals. This book will be of significant interest to students, researchers and debaters of animal ethics and welfare.