Companion or pet animals are an integral part of many societies. The ability of companion animals to positively affect our lives is therefore somewhat variable, and this is because there are numerous factors which may influence the way in which we respond to the presence of animals and to touching or talking to them. The type of stress (mental arithmetic, sound of a doorbell, telephone ring), the quality of the human support we have, our personality and relationship with the animal, and the behavior of the animal can all play a part.