The three primary data sets used in this analysis are the National Institutes of Health (NIH) academic institution data from 2003, the US Department of Agriculture (USDA) species and facilities data from 2003, and data on research animal vendors. The first set, which is referred to as the NIH grants data, consists of 1020 research institutions (academic and nonacademic) in the United States that receive grant awards for research utilizing research animals. For each institution, the data include the location (city and state), the number of NIH grant awards that utilize animals in 2003, and the award amount received in 2003. This data set was used as a proxy for rodent (rats and mice) use in the United States. Unlike other species of research animals, rodent use is not reported to any federal agency, so there is no census of rodents used in biomedical research. However, it has been estimated that rodents comprise approximately 95% of the animals utilized in research (Trull and Rich, 1999). Therefore, the total dollar amount of the NIH grants awarded to each institution was used as a proxy for the relative magnitude of rodent use at that institution.
The second data set, which is referred to as the USDA data,2 contains information on 985 research institutions (academic and nonacademic), their locations, and the numbers of animals utilized in research or breeding programs, by species (cats, dogs, rabbits, guinea pigs, hamsters, pigs, sheep, other farm animals, and nonhuman primates). Those two sets of data include all warm-blooded vertebrates (with the exception of rats, mice, and birds) used in research in the United States, and those vertebrates (including rats, mice, and birds) utilized in research supported by NIH funding. The one subgroup of research animals not described in those data sets are rats, mice, and birds utilized at research institutions not supported by NIH funding. This would include most commercial research institutions, such as pharmaceutical and biotech companies. Rodent vendors have estimated that 45% of shipments are to for-profit customers, suggesting that a large portion of the facilities that utilize rodents are not represented in the data sets used for this model.
The third data set, which is referred to as the vendor data, includes the major vendors that supply research animals in the United States, the locations of production facilities, and the species they supply. Of the 45 vendors in this data set, four vendors supply cats, 16 supply dogs, 20 supply rodents (rats and mice); some vendors supply multiple species.