Many animal species develop cancers spontaneously and are valuable for understanding the biology of sporadic cancer development in humans.  The genomes of some of these species have been sequenced recently, which greatly enhances the ability of researchers to perform cross-species comparisons.  These species are not genetically engineered or deliberately exposed to environmental carcinogens to initiate cancer.  However, because they generally have longer lifespans than laboratory animal models, their incidence of spontaneous malignancies is likely due to the effects of aging and environmental and dietary exposures that are comparable to human exposures.   Dogs, cats, horses, pigs, and goats are among the members of this group of model species. There is also work done with various primate species, such as baboons, chimpanzees, macaques, marmosets and tamarins.

Although the major use of spontaneous cancer models is to compare the biology with human, these animals are increasingly valuable for cross-comparison of response or resistance to the same clinical agents used for patients.  The knowledge obtained here will also provide benefits for the development and use of treatments for companion animals, conservation work or important agricultural livestock species as well. 

Explore the links on the left to learn more about cancer research involving these larger animal models.