Opinion Volume 5 Issue 3 - February 2018 DOI: 10.19080/BBOAJ.2018.04.555664 Biostat Biometrics Open Acc J Copyright © All rights are reserved by Helio Junji Shimozako Photographic Capture-Recapture for Free-Roaming Dog Population Estimation: Is It Possible to Optimize the Dog Photo-Identification? Shimozako HJ 1,2 , Euro de Barros Couto Junior 3 , Paulo Sergio Panse Silveira 1 and Eduardo Massad 1,4,5 1 School of Medicine and LIM 01-HCFM, University of São Paulo, São Paulo SP, Brazil 2 Faculty of Philosophy Sciences and Literature of Ribeirão Preto and RIDC NeuroMat, University of São Paulo, São Paulo SP, Brazil 3 São Paulo Municipal Government – Health Department of Public Agents – Patriarca Square, São Paulo SP, Brazil 4 School of Applied Mathematics, Getulio Vargas Foundation, Rio de Janeiro RJ, Brazil 5 London School of Hygiene and Tropical Medicine, University of London, London, UK Submission: February 13, 2018; Published: February 28, 2018 *Corresponding author: Helio Junji Shimozako, Faculty of Philosophy Sciences and Literature of Ribeirao Preto, University of São Paulo, Ribeirão Preto SP, Brazil, Tel: ; Email: Biostat Biometrics Open Acc J 5(3): BBOAJ.MS.ID.555664 (2018) 0084 Introduction Dogs are undoubtedly one of the most popular domestic animals in the world. Although most dogs are considered domiciliary and restricted animals, there are some of them that freely access the streets (they are known as free-roaming dogs). In the case of free-roaming dog population, there are some estimation techniques (or methods) that can be used to estimate the population abundance (i.e., there are indirect methods, surveys based on counts, lines, transects or points, radio telemetry and plenty of other different forms of capture- and-recapture methods) [1]. The capture-recapture method has been used for estimating wild animal populations and has been adapted for free-roaming dogs [1-4]. This method provides estimates of dog population sizes that can be important for the planning and development of appropriate control strategies, and to aid surveillance services [1-7]. Additionally, all descriptive data regarding the free-roaming dog population may generate information on dog control issues. This collected information can be utilized to inform dog control strategies at the local authority and to complement existing responsible dog ownership education programs [8]. Therefore, obtaining precise data of free-roaming dog population is interesting for preventive approach of veterinary public health. In this paper, it is discussed some limitations observed on photographic capture-recapture method when applied to estimate free-roaming dog population size. In addition, some directions and ideas to minimize such difficulties are pointed. All methods based on capture-recapture require a marking technique in order to identify each individual animal. Marking by photo-identification is an alternative that avoids physical contact between the researchers and the animals of unknown origin [2,3,7,9]. In addition, photo-identification avoids some of the problems traditionally associated with applying physical tags. For instance, natural marks cannot be shed, removed or fouled, and, depending on field practices, can also minimize the risk of confounding stress or behavioral issues [10]. The photo-identification process should consider that there is not misidentification of the animals [10]. However, some works have considered the possibility of misidentification [11- 14]. Moreover, one of the major criticisms of photo-identification studies is their perceived subjectivity, particularly in the initial identification and in the subsequent photo-matching [10]. The misidentification of photographs has been studied in the Biostatistics and Biometrics Open Access Journal ISSN: 2573-2633 Abstract It is important to estimate the population of free-roaming dogs because this information helps with planning and developing appropriate dog population control strategies as well as with epidemiological surveillance services. The photographic capture-recapture method has been used to estimate animal populations, including free-roaming dogs. This method consider the natural marks of phenotypical details that make a dog distinguishable from each other. However, the risk of misidentification is one of the limitations of the photographic capture-recapture method. In addition, the interference of the inhabitants of the study area is also other point to be considered. In this paper, it is discussed some current implications regarding to the application of photographic capture-recapture method to estimate free-roaming dog population. In addition, it is presented some possible directions to reduce the impact of such limitations. Keywords : Photographic capture-recapture; Free-roaming dog; Dog population estimation; Veterinary public health