Animal- assisted therapy (AAT), a type of therapy that involves animals as a means of treatment, has been discovered by the American psychologist Boris Levinson, 1960. The aim of this study was to determinate how animals can improve person’s emotional and physical well-being. The participants in this study were 111 people. Each participant was evaluated before and after the AAT intervention using objective psychological methods: Depression Anxiety Stress Scales (DASS, Lovibond, 1995, set of three self- report scales designed to measure the emotional states of depression, anxiety and stress). In summary we can report the following result which could be valuable in the field of psychological science, that animals may be used in therapy dealing with depression, anxiety and stress.