The literature now contains more than 1000 references to the use of a variety of animals in therapy. The terms used include Pet Therapy, Pet Assisted Therapy, Pet Facilitated Therapy. They reflect lack of agreement as to the role and effectiveness of animal use. Most are anecdotal descriptive studies lacking in scientific methodology. There are almost none in the psychiatric literature despite repeated claims of effectiveness in treating mental and emotional illness. This paper provides a review for the psychiatrist. It describes the development and use of rating scales to generate numerical values for statistical analysis, from videotaped observations of pet therapy sessions. Blind ratings yielded high inter-rater correlations. Although a pilot study, the results indicate the feasibility of designing definitive studies to evaluate the claims of animal enthusiasts. Valuable insights were gained which help to clarify the respective roles of animals and therapists.