Pets play a greater role in our emotional and physical health than ever before, says the Purdue University professor who is co-author of his revised edition of Between Pets and People: The Importance of Animal Companionship. The book by Alan M. Beck of Purdue's School of Veterinary Medicine and Aaron H. Katcher, psychiatrist and professor emeritus at the University of Pennsylvania, explores the emotional and physical benefits of owning a pet and analyzes the complex relationship between people and pets. "The study of the importance of the relationship between people and animals is a growing field and has the potential to be part of the whole human-health field," says Beck, director of Purdue's Center for Applied Ethology and Human-Animal Interaction. "The social milieu on where animals fit into society has really changed in the last 13 years. We've gone from recognizing the potential of animals being a significant positive contribution to certain populations, such as the elderly, to actual documentation." Beck and Katcher note a 1992 study by an Australian cardiologist of 5,000 people who visited a clinic to find ways to reduce heart disease. The study found that people with pets had lower blood pressure and lower blood fat levels than those without pets, even though the two groups were alike in diet and exercise. The authors also point to the trend by nursing homes to incorporate animals into the routine and environment for patients. For example, in the early 1980s nursing homes typically did not allow pets to visit patients, while today nearly half of the homes have an organized program for animal therapy, Beck says. In addition to exploring physical benefits, the book covers such topics as pets as family members, pets as therapists, talking to pets, and how pets can teach us to become better companions to friends and family. The book also has a list of Web sites by such organizations as Canine Companions for Independence and the American Kennel Club. While pets provide health benefits, they can create problems, Beck and Katcher say. "There is no medicine that doesn't have some side effects," Beck says. For example, more pet ownership has public-health implications such as more dog bites, he notes. And some people whose pets die grieve to the point of illness, he says. But grief over the loss of an animal is not new, Beck says. Ancient Egyptians shaved their eyebrows after their cats died, and the Roman emperor Caligula had his horse entombed.