Rat, Animal Model

Most rats used in cancer research are Fischer 344 rats, which are white albinos rats (photo on the right). F344 rats are a "pure strain": it means they have been obtained by multiple sequential (brother x sister) crossings. Any F344 rat is genetically "very close" to any other F344 rat. Pros: studies done in different labs, or at different times, yield reproducible results; each study requires fewer animals than would a "non-pure" strain study. Cons: humans are not "pure strain" and F344 genetic homogeneity is far from people variability

Many other strains (pure or not) are used, but less often, e.g., Sprague Dawley rats; Wistar rats; ACI/N rats; BDIX rats; CD rats; Donryu rats; LIO rats; Charles River rats (? C.R. is more a supplier than a strain); Zucker fa/fa obese rats; DB6 rats;

I included the image of a brown hooded rat on Chemoprevention Database home page (here, on left), because it looks more intelligent and alert than the white F344 rat.