In this article, we reviewed how the therapy animals for animal assisted intervention (AAI) could be treated ethically in the aspects of animal welfare. Our goal is to reexamine the animal-human partnership from the animal's viewpoint to see what the benefits might be for the animal, or to see if the raising, training, and deployment of assistance and therapy animals is causing significant degradation in animal welfare. Also, we want to make an impression for AAI therapists to examine their ethical responsibility for the welfare of their therapeutic assisting animals. Animal assisted psychotherapist must respect the integrity of the animals and recognize that their rights and safety are safeguarded. In this article, we intend to provide recent advanced knowledge on the animal welfare and ethical reference in the filed of animal-assisted intervention.