Published online by Cambridge University Press: 19 October 2009
The Florida cotton rat, Sigmodon hispidus, has become established as a laboratory animal largely because it is the best known host of the filariid worm, Litomosoides carinii, which is used in routine screening tests for filariacides.
Cotton rats are unsuitable for infecting when very small, and as the filariae take several months to develop enough for the purpose of the test, most of the cotton rats are fully grown at the time of testing. Their weight range is 125–225 g., average about 170 g.