Study design and rationale for the Dog Aging Project Pack: a prospective, long-term, longitudinal, observational study of biological and environmental determinants of healthy aging in US companion dogs

Companion dogs are a valuable source of translational discovery about the basic biology of aging because of their well-characterized genome, phenotypic variation in lifespan, aging, and disease profiles, and diverse environmental exposures shared with their human owners. The Dog Aging Project (DAP)’s prospective, longitudinal open cohort study was begun in 2019 to investigate the biological and environmental determinants of healthy aging in companion dogs. As of December 31, 2024, the study has enrolled 50,188 companion dogs across all 50 US states and the District of Columbia, including over half with follow-up data, spanning up to five years, and 14,978 documented deaths. The DAP is a community science research program in which owners volunteer to provide detailed longitudinal information about their dogs. This manuscript describes the recruitment and retention of this study population, known as the DAP Pack, including the data collection processes, and the means by which DAP Open Data are shared with the research community. The goals of this manuscript are to present the detailed methodology of the DAP as a resource to support authors and readers of DAP publications, to provide the scientific community with a framework to support the design of similar future studies, and to facilitate use of DAP data by investigators with Open Data access.