Animal ethics is a growing community concern requiring effective responses from professionals in animal-related fields such as veterinary and animal science. Limited research indicates that veterinarians regularly face ethical dilemmas in relation to animal ethics issues, causing moral distress. However, while animal ethics teaching in veterinary and other animal science courses is growing internationally, it is still a relatively new discipline with no common approach or competencies for developing ethical behaviour toward animals.This thesis is that animal ethics education should be based on a scientific approach to morality, building on existing scientific approaches to morality and moral behaviour in philosophy, neurobiology, evolutionary biology and moral psychology to identify and develop the capacity for veterinarians and others in animal-related fields to address animal ethics issues. It includes six studies with a particular focus on quantitative methodologies to measure moral judgment and moral sensitivity, two of four previously identified components of moral behaviour.Based on a well-validated test of moral judgment on human ethics issues, the first study involved development of the Veterinary Defining Issues Test (VetDIT) to identify preferred levels of moral reasoning on animal ethics issues using three veterinary-related issues. Using this test, students of veterinary medicine, animal science and veterinary technology, at different stages of their programs in one Australian university, showed similar preferences for three types of moral reasoning i.e.Personal Interest, Maintaining Norms and Universal Principles on human ethics issues, but used more principled reasoning and less personal interest reasoning on animal ethics issues.In the second study, the VetDIT was refined and a third version created to use as a post test in a moral judgment intervention study, which included moral development theory and a new template based on a universal ethical decision-making model, Preston's Ethic of Response. This study found a three hour small group interactive workshop highly effective in developing principled reasoning as demonstrated by VetDIT moral judgment scores on pre-and post-tests. A lecture format using similar content had no effect.The third study for this thesis identified that principled reasoning was not exclusive to animalrelated professions, with similarly high levels of principled reasoning by human medicine and arts students. However, arts students showed more personal interest reasoning on both human and animal issues than students of veterinary and human medicine, veterinary technology and animal ii science and less maintaining norms reasoning on animal ethics issues. Human medical students showed more maintaining norms reasoning on animal ethics issues than students in animal-related disciplines.A complex relationship between intuitive action choices and moral reasoning types was demonstrated in a fourth study using the VetDIT responses of 646 students in five animal-and two non-...