The dog is one of the most popular pet in the world. However, if this population is out of control, injuries against human beings, other animals and environment can occur. Therefore, studies related to dog population are important in order to optimize methods and strategies of control. This book evaluates the photo-identification technique for dogs and presents a suggestion to improve the photographic capture-recapture method. The text is divided in four parts: characterization of the stray dog population; evaluation of photo-identification technique for dogs; evaluation of four methods of dog population estimation based on capture-recapture methods; finally, the reports of our experience. This work should help professionals that are involved with Veterinary Public Health, Epidemiology, Ecology and Animal Welfare, and all people interested in this subject.