The Rat Genome Database has developed an ontology-based database and data mining tool to integrate rat phenotype data. The database uses four main ontologies - strain, clinical measurement, measurement method, and experimental conditions - to annotate phenotype data from various projects. This allows users to search and filter phenotype data based on these categories to compare results across studies and assist in choosing appropriate rat strains for their research. The tool also links phenotype data to genomic and genetic information to further understanding of variations.