References

USDA Definition Of An Animal

From the USDA Animal Welfare Act Regulations, Part 1, Definitions: 
“Animal means any live or dead dog, cat, nonhuman primate, guinea pig, hamster, rabbit, or any other warm blooded animal, which is being used, or is intended for use for research, teaching, testing, experimentation, or exhibition purposes, or as a pet. This term excludes: Birds, rats, of the genus Rattus and mice of the genus Mus bred for use in research, and horses not used for research purposes and other farm animal, such as, but not limited to livestock or poultry used or intended for use for improving animal nutrition, breeding, management, or production efficiency, or for improving the quality of food or fiber. With respect to a dog, the term means all dogs, including those used for hunting, security, or breeding purposes.” 
http://www.access.gpo.gov/nara/cfr/waisidx/9cfr1.html