Participants have two study sessions, each lasting about 20 minutes on two different days. In one session, they visit with an animal assistant therapy dog and its handler. In the other session they engage in a conversation that the patient identifies as non-stressful. Patients are asked to fill out four forms before and after each session with questions and statements about their pain, attitude towards pets, symptoms they might be having, and demographic information, such as age, sex, marital status, and so forth. On four separate occasions, 1 teaspoon of blood is drawn and a swab of saliva is collected from the mouth up to an hour after the session.